• Repeating decimals are irrational

    From wij@wyniijj5@gmail.com to comp.lang.c++ on Tue Mar 26 22:51:40 2024
    From Newsgroup: comp.lang.c++

    Snipet from https://sourceforge.net/projects/cscall/files/MisFiles/RealNumber-en.txt/download
    ...
    Real Nunmber(ℝ)::= {x| x is represented by n-ary <fixed_point_number>, the
    digits may be infinitely long }
    Note: This definition implies that repeating decimals are irrational number.
    Let's list a common magic proof in the way as a brief explanation:
    (1) x= 0.999...
    (2) 10x= 9+x // 10x= 9.999...
    (3) 9x=9
    (4) x=1
    Ans: There is no axiom or theorem to prove (1) => (2).
    Note: If the steps of converting a number x to <fixed_point_number> is not
    finite, x is not a ratio of two integers, because the following
    statement is always true: ∀x,a∈ℚ, x-a∈ℚ
    ---End of quote
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Michael S@already5chosen@yahoo.com to comp.lang.c++ on Tue Mar 26 17:11:26 2024
    From Newsgroup: comp.lang.c++

    On Tue, 26 Mar 2024 22:51:40 +0800
    wij <wyniijj5@gmail.com> wrote:
    Snipet from https://sourceforge.net/projects/cscall/files/MisFiles/RealNumber-en.txt/download

    ...
    Real Nunmber(ℝ)::= {x| x is represented by n-ary
    <fixed_point_number>, the digits may be infinitely long }

    Note: This definition implies that repeating decimals are
    irrational number. Let's list a common magic proof in the way as a
    brief explanation: (1) x= 0.999...
    (2) 10x= 9+x // 10x= 9.999...
    (3) 9x=9
    (4) x=1
    Ans: There is no axiom or theorem to prove (1) => (2).

    Note: If the steps of converting a number x to
    <fixed_point_number> is not finite, x is not a ratio of two integers,
    because the following statement is always true: ∀x,a∈ℚ, x-a∈ℚ

    ---End of quote

    I don't know what you meant to say, but repeating (a.k.a. periodic)
    decimals are most certainly rational numbers. I think that proving it
    would be rather easy although I didn't try to do it in rigorous
    manner. The idea of proof is multiplying repeating decimal with period P
    by (10**P-1) will produce finite decimal. Which is obviously rational.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Ben Bacarisse@ben.usenet@bsb.me.uk to comp.lang.c++ on Tue Mar 26 16:13:48 2024
    From Newsgroup: comp.lang.c++

    Michael S <already5chosen@yahoo.com> writes:

    On Tue, 26 Mar 2024 22:51:40 +0800
    wij <wyniijj5@gmail.com> wrote:
    <nothing relating to C++>

    I don't know what you meant to say,

    Indeed! But it was not about C++, that's for sure. He's riding this
    hobby horse around some maths groups, but there's no reason to get comp.lang.c++ involved.
    --
    Ben.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Tue Mar 26 13:13:18 2024
    From Newsgroup: comp.lang.c++

    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Wed Mar 27 05:43:32 2024
    From Newsgroup: comp.lang.c++

    On Tue, 2024-03-26 at 13:13 -0700, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)
    Just repeat the pattern infinitely, then it is irrational.
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Paavo Helde@eesnimi@osa.pri.ee to comp.lang.c++ on Tue Mar 26 23:51:23 2024
    From Newsgroup: comp.lang.c++

    26.03.2024 22:13 Chris M. Thomasson kirjutas:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Any number represented by stored digits on Earth has finite number of
    digits (because Earth is finite) and therefore is rational, regardless
    of how the digits are generated.

    If you want to represent irrational numbers you need to use some other encoding schema, e.g. "sqrt(2)" (8 bytes, voila!).
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Tue Mar 26 19:42:47 2024
    From Newsgroup: comp.lang.c++

    On 3/26/2024 2:51 PM, Paavo Helde wrote:
    26.03.2024 22:13 Chris M. Thomasson kirjutas:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Any number represented by stored digits on Earth has finite number of
    digits (because Earth is finite) and therefore is rational, regardless
    of how the digits are generated.

    Even with a TRNG?



    If you want to represent irrational numbers you need to use some other encoding schema, e.g. "sqrt(2)" (8 bytes, voila!).

    pi? ;^D

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Paavo Helde@eesnimi@osa.pri.ee to comp.lang.c++ on Wed Mar 27 11:47:11 2024
    From Newsgroup: comp.lang.c++

    27.03.2024 04:42 Chris M. Thomasson kirjutas:
    On 3/26/2024 2:51 PM, Paavo Helde wrote:
    26.03.2024 22:13 Chris M. Thomasson kirjutas:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Any number represented by stored digits on Earth has finite number of
    digits (because Earth is finite) and therefore is rational, regardless
    of how the digits are generated.

    Even with a TRNG?


    TRNG is defined as a device having access to a "physical entropy
    source". For producing an irrational number it ought to produce an
    infinite never-repeating sequence of digits.

    It's not clear if any physical mechanism would in principle produce a non-repeating infinite sequence of digits, the fact that the world is quantized might rather speak against it. Even if it did, the lifetime of
    a physical device is finite, so it can only produce a finite sequence of digits. Even if the lifetime of the hypothetical device would be
    infinite, we do not possess the infinite space and time to store the
    result. Such infinities are strictly the territory of mathematics, in
    real world we can have only finite sequence of digits.

    A finite sequence of digits represents a rational number. For example, a number which I just constructed by throwing my 10-euro-cent TRNG is 0.10010111011 (in binary) which can be expressed as a ratio of two
    integers by trivial point shifting:

    0.10010111011 (binary) = 10010111011 (binary) / 2^11 = 1211 / 2048



    If you want to represent irrational numbers you need to use some other
    encoding schema, e.g. "sqrt(2)" (8 bytes, voila!).

    pi? ;^D


    In mathematics, a notion like pi actually defines an irrational number
    by fixing its properties. For some such irrational numbers it is
    possible to give an infinite algorithm which produces the sequence of
    its digits. The funny thing is that after fixing the number there is no randomness any more, so e.g. a machine computing subsequent digits of pi
    would make a pretty poor RNG ;-)

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 11:31:17 2024
    From Newsgroup: comp.lang.c++

    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number. I am not convinced it is meaningful
    to talk about its properties at all.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 12:50:46 2024
    From Newsgroup: comp.lang.c++

    On 26/03/2024 22:43, wij wrote:
    On Tue, 2024-03-26 at 13:13 -0700, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) cannot terminate, 1/7 != 0.(142857)


    Nonsense.

    Simply stating random things does not make them so.

    I recommend you stick to C++ in this C++ newsgroup.

    As for your maths, you'd do better learning some basics of the
    mathematics of real numbers and rational numbers, and that being able to
    find the Unicode characters for some logic symbols does not mean you understand how to write a proof.


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 13:10:30 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 10:47, Paavo Helde wrote:
    In mathematics, a notion like pi actually defines an irrational number
    by fixing its properties. For some such irrational numbers it is
    possible to give an infinite algorithm which produces the sequence of
    its digits. The funny thing is that after fixing the number there is no randomness any more, so e.g. a machine computing subsequent digits of pi would make a pretty poor RNG ;-)


    The digits would actually make quite a good RNG - if you had a practical
    way to keep getting the digits. It is not proven, but it is strongly suspected that pi is normal in all bases - you will get an even
    distribution of digits over time, and any finite sequence of digits will
    occur equally often as other sequences of the same length. This is the
    key characteristic of an unbiased random source. No test of the
    sequence of digits could determine that it is not from a random source.

    There is an algorithm that lets you find digits of the hexadecimal
    expansion of pi without finding all the previous digits, which could be
    useful here.

    But it won't be very good for security purposes or other such uses of
    random numbers!


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Wed Mar 27 20:12:38 2024
    From Newsgroup: comp.lang.c++

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:
    On Tue, 2024-03-26 at 13:13 -0700, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) cannot terminate, 1/7 != 0.(142857)


    Nonsense.

    I am surprise your math. knowledge is so low worse than teenagers.
    Simply stating random things does not make them so.

    I recommend you stick to C++ in this C++ newsgroup.

    I know. You 'occupied' c/c++ forum and think you are speech police.
    For now, this discussion is mainly in comp.theory
    But you have shown your knowledge is so so low, don't go there waste our time.
    As for your maths, you'd do better learning some basics of the
    mathematics of real numbers and rational numbers, and that being able to find the Unicode characters for some logic symbols does not mean you understand how to write a proof.


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Ralf Goertz@me@myprovider.invalid to comp.lang.c++ on Wed Mar 27 13:57:02 2024
    From Newsgroup: comp.lang.c++

    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:
    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.
    Use the standard trick:
    x=0.[142857] => 1,000,000*x=142857.[142857]
    subtract the first equation from the second:
    999,999*x=142857 => x=142857/999,999=1/7
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Wed Mar 27 21:32:12 2024
    From Newsgroup: comp.lang.c++

    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote: 

    Just repeat the pattern infinitely, then it is irrational. 

    Nonsense.
     
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
     

    Nonsense.
     

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7

    To determine whether a number x is rational or not, we can repeatedly subtract rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is simply false by sematics.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Wed Mar 27 21:49:33 2024
    From Newsgroup: comp.lang.c++

    On Wed, 2024-03-27 at 21:32 +0800, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote: 

    Just repeat the pattern infinitely, then it is irrational. 

    Nonsense.
     
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
     

    Nonsense.
     

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is simply false by sematics.


    By the way, this came to me: ε-δ method was used by people to think that we can 
    make x-a approach 0 to arbitrary precision, then conclude that the 'limit' is 0,
    'therefore', repeating decimal is rational !!!
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 15:51:17 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 13:12, wij wrote:
    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:
    On Tue, 2024-03-26 at 13:13 -0700, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>> cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.


    It's a long time ago and hard to be sure, but I believe I knew that real numbers were rational if and only if their decimal expansion was
    repeating before I was a teenager. And I don't believe that rational
    numbers or decimal expansions have changed their nature since then.

    (And as a maths student I wrote an essay on a derivation of the real
    numbers from the axioms of Zermelo-Fraenkel set theory, proving each
    step along the way, proving the equivalence between constructions from
    decimal - or n-ary - representations to constructions based on
    completing the rationals, proving the existence of irrational numbers,
    and establishing the cardinality of the real numbers. I might be a bit
    out of practice, but I know what I am talking about.)


    If you hold strange views on a mathematical topic that runs contrary to
    the established mainstream, especially something so simple and non-contentious, you have to be prepared to be treated as a fool and
    ridiculed as a flat-earther or a trisector.

    But just for your benefit, I had a quick look at the start of your "RealNumber-en.txt" file - the section on Real Numbers.

    1. /You/ don't get to define real numbers. That is a well-established
    term in mathematics, and you don't get to replace it with waffle-worded
    text.

    2. In mathematics, you don't get to say "a definition is not provided"
    and then "this definition implies ...". Make /rigorous/ definitions,
    and /prove/ their definitions. What you are writing here is not
    mathematics - it's a C-grade response to a high-school test question
    "What is a real number?".

    3. You cannot claim what this definition (such as it is) says about
    irrational numbers, when you have not said what rational or irrational
    numbers are. Since you are using your own broken definition for reals,
    who knows what mistaken ideas you might have about rationals and
    irrationals.

    4. Arithmetic on repeating decimals is well defined, and if x = 0.999...
    then 10.x is 9 + x. This /is/ provable.

    5. Please don't try and talk about axioms. You are /very/ far from that
    level of rigour.

    6. Even if your claim that 0.999... != 1 were true, and even if you had
    proven it, it would not have the implications you are claiming.

    7. Noting that the rationals are closed under subtraction has not the slightest bearing on anything that you have been claiming. It's
    plausible that it might be involved in a step of the proof of your
    claims - if such a proof were possible. But you haven't even made the
    vaguest suggestions of a proof - you simply throw out your claims and
    expect them to be believed.

    (The rest of the document is too jumbled and unclear to critique. I appreciate that English is not your first language, but you seem to be
    able to write it well enough when you try, so I blame your mathematics,
    not your language skills.)


    I expect you've been told all of this before.


    Simply stating random things does not make them so.

    I recommend you stick to C++ in this C++ newsgroup.


    I know. You 'occupied' c/c++ forum and think you are speech police.

    I have not "occupied" anything. This is a newsgroup primarily concerned
    with discussions of C++ - that's in the name of the group.

    I also recommend you stick to C++ because you apparently have an
    interest in and knowledge of C++, and as far as I have noticed, you talk sensibly about the language.

    For now, this discussion is mainly in comp.theory

    You started a new thread in comp.lang.c++. I don't know what there
    might or might not be in comp.theory - anything there is irrelevant to
    this discussion. (I can't see how your post is remotely on-topic for computational theory either.)

    But you have shown your knowledge is so so low, don't go there waste our time.

    I don't follow comp.theory. But I have seen a few threads over the
    years which have "leaked" from there to groups that I do follow, and I
    feel confident in guessing that few people there share your ideas about
    real numbers.


    As for your maths, you'd do better learning some basics of the
    mathematics of real numbers and rational numbers, and that being able to
    find the Unicode characters for some logic symbols does not mean you
    understand how to write a proof.





    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 16:01:10 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>>>> cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x.

    I assume that when you say "rational numbers a?", you mean numbers with
    finite decimal expansions?

    Your method could, I suppose, be used to prove that x is rational - but
    not to prove that it is irrational. It is not particularly helpful,
    unless you are using it as some way to build up the rationals
    inductively from a starting point of "assumed" rationals.

    If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational.

    Correct.

    Otherwise, x is irrational.

    Incorrect.

    All you have proven is that you have not picked appropriate rationals in
    the sequence, or that x is a number with a non-finite decimal expansion.
    You haven't demonstrated that it is irrational.

    Your method here doesn't give you anything new. It boils down to saying
    that if we assume that all rationals have finite decimal expansions, we
    can prove that numbers without finite decimal expansions are not
    rational - and that's a simple tautology. The assumption is, of course, wrong.


    If x is a repeating decimal, proposition "repeating decimal is rational" is simply false by sematics.


    Incorrect.



    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Wed Mar 27 16:02:45 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>>>> cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    What do you think the decimal expansion of 1/7 is?



    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Thu Mar 28 00:05:00 2024
    From Newsgroup: comp.lang.c++

    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
      
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
      

    Nonsense.
      

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational
    What do you think the decimal expansion of 1/7 is?

    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure
    never terminates which means the conversion is never complete.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 13:17:29 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 3:31 AM, David Brown wrote:
    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).

    ;^)


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number.  I am not convinced it is meaningful
    to talk about its properties at all.


    Well, it would be a "number" at any finite view of it? Or, is that just moronic thinking? For some reason it makes me think of infinite
    convergents of continued fractions. Can we gain a rational that can approximate any irrational up to a certain precision, so to speak?
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 13:29:06 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 6:32 AM, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>>>> cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not,[...]

    Check for a period...


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 13:34:22 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 8:01 AM, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>>>>> cannot terminate, 1/7 != 0.(142857)

    Nonsense.

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly
    subtract
    rational numbers a? from x.

    I assume that when you say "rational numbers a?", you mean numbers with finite decimal expansions?

    Your method could, I suppose, be used to prove that x is rational - but
    not to prove that it is irrational.  It is not particularly helpful,
    unless you are using it as some way to build up the rationals
    inductively from a starting point of "assumed" rationals.

    If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational.

    Correct.

    Otherwise, x is irrational.

    Incorrect.

    All you have proven is that you have not picked appropriate rationals in
    the sequence, or that x is a number with a non-finite decimal expansion.
     You haven't demonstrated that it is irrational.

    Your method here doesn't give you anything new.  It boils down to saying that if we assume that all rationals have finite decimal expansions, we
    can prove that numbers without finite decimal expansions are not
    rational - and that's a simple tautology.  The assumption is, of course, wrong.


    If x is a repeating decimal, proposition "repeating decimal is
    rational" is
    simply false by sematics.


    Incorrect.





    Think of doing long division, as soon as you hit a period (aka the same number), you can stop. Fair enough?

    base 10:

    1 / 3 = .(3), .3..., whatever

    We will notice during long division that a period has been encountered,
    there we can stop iteration, and say .3 repeating. Fair enough? Its fun
    to record how many steps to took to hit a period. Fun... Akin to escape
    time fractals wrt how many iterations it took for a number to escape a
    given limit, so to speak.

    Make any sense? Or stupid? ;^o
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Marcel Mueller@news.5.maazl@spamgourmet.org to comp.lang.c++ on Wed Mar 27 21:34:50 2024
    From Newsgroup: comp.lang.c++

    Am 26.03.24 um 16:11 schrieb Michael S:
    I don't know what you meant to say, but repeating (a.k.a. periodic)
    decimals are most certainly rational numbers.

    Exactly.

    I think that proving it
    would be rather easy although I didn't try to do it in rigorous
    manner.

    They are always rational numbers because any repeated sequence is just equivalent to a denominator withe base^length - 1, e.g.
    0,(142857) = 142857 / 999999

    The idea of proof is multiplying repeating decimal with period P
    by (10**P-1) will produce finite decimal. Which is obviously rational.

    Indeed.


    Marcel

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 13:40:59 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is >>> simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you
    will. In 1/7, say it took 6 iterations to hit the period... Sound okay?
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 13:45:54 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 5:10 AM, David Brown wrote:
    On 27/03/2024 10:47, Paavo Helde wrote:
    In mathematics, a notion like pi actually defines an irrational number
    by fixing its properties. For some such irrational numbers it is
    possible to give an infinite algorithm which produces the sequence of
    its digits. The funny thing is that after fixing the number there is
    no randomness any more, so e.g. a machine computing subsequent digits
    of pi would make a pretty poor RNG ;-)


    The digits would actually make quite a good RNG - if you had a practical
    way to keep getting the digits.

    Fwiw, here is an example of a highly non-practical way to reap base 2
    symbols to construct a number:

    https://groups.google.com/g/comp.lang.c++/c/7u_rLgQe86k/m/fYU9SnuAFQAJ

    ;^D



    It is not proven, but it is strongly
    suspected that pi is normal in all bases - you will get an even
    distribution of digits over time, and any finite sequence of digits will occur equally often as other sequences of the same length.  This is the
    key characteristic of an unbiased random source.  No test of the
    sequence of digits could determine that it is not from a random source.

    There is an algorithm that lets you find digits of the hexadecimal
    expansion of pi without finding all the previous digits, which could be useful here.

    But it won't be very good for security purposes or other such uses of
    random numbers!



    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Thu Mar 28 05:39:58 2024
    From Newsgroup: comp.lang.c++

    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
       
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
       

    Nonsense.
       

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you
    will. In 1/7, say it took 6 iterations to hit the period... Sound okay?
    Stupid! It is an infinite string. Cycle or period can only be determined for finite string.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 15:10:03 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 2:39 PM, wij wrote:
    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>>>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>> never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you
    will. In 1/7, say it took 6 iterations to hit the period... Sound okay?

    Stupid! It is an infinite string.

    Not sure how to respond to that. A cycle is a finite thingy... ;^)


    Cycle or period can only be determined for
    finite string.




    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 15:14:36 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 2:39 PM, wij wrote:
    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>>>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>> never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you
    will. In 1/7, say it took 6 iterations to hit the period... Sound okay?

    Stupid! It is an infinite string. Cycle or period can only be determined for finite string.



    For some reason, I think you might be misunderstanding me.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 19:20:16 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 3:31 AM, David Brown wrote:
    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number.  I am not convinced it is meaningful
    to talk about its properties at all.


    Say you iterated up to, say 7 digits from a TRNG:

    .3274836

    We say, okay:

    0.3274836 3274836 3274836

    Can we say this is rational? How about:

    1091612/3333333

    ? Fair enough or off base, so to speak... ?
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Wed Mar 27 21:52:02 2024
    From Newsgroup: comp.lang.c++

    On 3/27/2024 5:12 AM, wij wrote:
    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:
    On Tue, 2024-03-26 at 13:13 -0700, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i) >>> cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Oh wow. What made you say that?

    Just a bit interested? Humm...



    Simply stating random things does not make them so.

    I recommend you stick to C++ in this C++ newsgroup.


    I know. You 'occupied' c/c++ forum and think you are speech police.
    For now, this discussion is mainly in comp.theory
    But you have shown your knowledge is so so low, don't go there waste our time.

    As for your maths, you'd do better learning some basics of the
    mathematics of real numbers and rational numbers, and that being able to
    find the Unicode characters for some logic symbols does not mean you
    understand how to write a proof.





    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Thu Mar 28 18:16:04 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is >>> simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure never terminates which means the conversion is never complete.


    It is a repeating decimal. If you try to write it all out, then I agree
    you will not finish. That does not mean it is not the decimal expansion
    of 1/7 - the list of multiples of (negative) powers of 10 which sum up
    to 1/7. You just need a better notation so that you can finish the task
    - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even
    though you could not write it out long-hand, and you agree that 1/7 i rational. And clearly 0.(142857) is a repeating decimal, since that's
    what the notation means.

    I can't see how you can still misunderstand this.




    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Thu Mar 28 18:17:59 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 22:39, wij wrote:
    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>>>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>> never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you
    will. In 1/7, say it took 6 iterations to hit the period... Sound okay?

    Stupid! It is an infinite string. Cycle or period can only be determined for finite string.


    Nonsense.

    You /know/ the cycle for the infinite decimal expansion for 1/7 - it is
    the digits "142857", repeated every 6 digits in the decimal expansion.
    Again, that's what the notation 0.(142857) - /your/ choice of notation,
    so presumably familiar to you - means.




    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Thu Mar 28 18:47:21 2024
    From Newsgroup: comp.lang.c++

    On 27/03/2024 21:17, Chris M. Thomasson wrote:
    On 3/27/2024 3:31 AM, David Brown wrote:
    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).

    ;^)


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number.  I am not convinced it is
    meaningful to talk about its properties at all.


    Well, it would be a "number" at any finite view of it? Or, is that just moronic thinking?

    It is not a defined number in any way - you are explicitly using a
    procedure which does not give any defined or deterministic results. How
    could it be a number when no two people could agree to its value?

    Now, if you were to take a TRNG and generate a series of digits, writing
    each one down as you go along, then at any given time you would have a
    finite decimal expansion which would be a number (a rational, if that
    matters to you). But that is a particular instance of creating such a
    number - the procedure you describe does not define a number nor is it a number in itself.

    For some reason it makes me think of infinite
    convergents of continued fractions.

    I am not sure you are helping yourself or anyone else there. A sequence
    of digits obtained randomly does not converge.

    Can we gain a rational that can
    approximate any irrational up to a certain precision, so to speak?

    Of course we can. That is a completely separate issue.

    If you have a real number "x" (positive for simplicity), and a precision
    "e", then we can easily find a rational number q such that |x - q| < e.
    We do so by letting "i" be an integer greater than 1/e. Let "j" be the
    first integer less than or equal to i * x.

    So
    j <= (i * x) < (j + 1)

    and thus

    j / i <= x < (j + 1) / i

    q0 = j / i and q1 = (j + 1) / i are both rational numbers, and "x" lies between them.

    q1 - q0 = 1 / i, which is less than "e" since "i" is greater than 1/e.

    So since (q1 - q0) < e, and q0 <= x < q1, then we can see that "x" is "trapped" between two rationals that are both less than "e" from "x".

    You can approximate any real number as closely as you like with a series
    of rational numbers. That is basically what it means to say that the
    real numbers "complete" the rationals - the fill in the gaps that can be expressed as the limits of bounded sequences of rationals where the
    limit is not itself a rational.




    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Fri Mar 29 02:23:46 2024
    From Newsgroup: comp.lang.c++

    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
       
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
       

    Nonsense.
       

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree you will not finish.  That does not mean it is not the decimal expansion
    of 1/7 - the list of multiples of (negative) powers of 10 which sum up
    to 1/7.  You just need a better notation so that you can finish the task
    - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even
    though you could not write it out long-hand, and you agree that 1/7 i rational.  And clearly 0.(142857) is a repeating decimal, since that's
    what the notation means.

    I can't see how you can still misunderstand this.

    You are restating your assertion without proof, again. I have provided mine. (If you say that is you proof, I will say it is invalid).
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Fri Mar 29 02:25:28 2024
    From Newsgroup: comp.lang.c++

    On Thu, 2024-03-28 at 18:17 +0100, David Brown wrote:
    On 27/03/2024 22:39, wij wrote:
    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
        
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
        

    Nonsense.
        

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure
    never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you will. In 1/7, say it took 6 iterations to hit the period... Sound okay?

    Stupid! It is an infinite string. Cycle or period can only be determined for
    finite string.


    Nonsense.

    You /know/ the cycle for the infinite decimal expansion for 1/7 - it is
    the digits "142857", repeated every 6 digits in the decimal expansion. Again, that's what the notation 0.(142857) - /your/ choice of notation,
    so presumably familiar to you - means.

    "0.(142857)" is pre-determined and specified not detected. (unless I misunderstood
    what Chris said)
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Thu Mar 28 12:41:28 2024
    From Newsgroup: comp.lang.c++

    On 3/28/2024 10:47 AM, David Brown wrote:
    On 27/03/2024 21:17, Chris M. Thomasson wrote:
    On 3/27/2024 3:31 AM, David Brown wrote:
    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).

    ;^)


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number.  I am not convinced it is
    meaningful to talk about its properties at all.


    Well, it would be a "number" at any finite view of it? Or, is that
    just moronic thinking?

    It is not a defined number in any way - you are explicitly using a
    procedure which does not give any defined or deterministic results.  How could it be a number when no two people could agree to its value?

    Now, if you were to take a TRNG and generate a series of digits, writing each one down as you go along, then at any given time you would have a finite decimal expansion which would be a number (a rational, if that matters to you).  But that is a particular instance of creating such a number - the procedure you describe does not define a number nor is it a number in itself.

    Would it be fair to say it defines a random number that is an actual
    number at every finite step... Is that a stupid thought?


    For some reason it makes me think of infinite convergents of continued
    fractions.

    I am not sure you are helping yourself or anyone else there.

    Well, shit happens. Just some fun with numbers? ;^)


    A sequence
    of digits obtained randomly does not converge.

    True, but at every "step", it can be a rational? I just think it can be
    a fun study, so to speak...


    Can we gain a rational that can approximate any irrational up to a
    certain precision, so to speak?

    Of course we can.  That is a completely separate issue.

    Yeah. Well, okay. I agree.


    If you have a real number "x" (positive for simplicity), and a precision "e", then we can easily find a rational number q such that |x - q| < e.
    We do so by letting "i" be an integer greater than 1/e.  Let "j" be the first integer less than or equal to i * x.

    Using a TRNG to "generate" x, and a precision, say when we stop drawing
    digits from the TRNG, would create a rational. Right?


    So
        j <= (i * x) < (j + 1)

    and thus

        j / i <= x < (j + 1) / i

    q0 = j / i and q1 = (j + 1) / i are both rational numbers, and "x" lies between them.

    q1 - q0 = 1 / i, which is less than "e" since "i" is greater than 1/e.

    So since (q1 - q0) < e, and q0 <= x < q1, then we can see that "x" is "trapped" between two rationals that are both less than "e" from "x".

    You can approximate any real number as closely as you like with a series
    of rational numbers.  That is basically what it means to say that the
    real numbers "complete" the rationals - the fill in the gaps that can be expressed as the limits of bounded sequences of rationals where the
    limit is not itself a rational.

    Are you saying that a number constructed digit-by-digit using a TRNG is undefined? Its not a number, however it creates many numbers during the construction process? Fair enough?


    Ahhh shit, this is just me having some fun. Sorry.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From usenet@usenet@stegropa.de (Stefan =?utf-8?Q?Gro=C3=9Fe?= Pawig) to comp.lang.c++ on Thu Mar 28 21:33:30 2024
    From Newsgroup: comp.lang.c++

    wij <wyniijj5@gmail.com> writes:
    Snipet from https://sourceforge.net/projects/cscall/files/MisFiles/RealNumber-en.txt/download

    ...
    Real Nunmber(ℝ)::= {x| x is represented by n-ary <fixed_point_number>, the
    digits may be infinitely long }

    Note: This definition implies that repeating decimals are irrational number.
    Let's list a common magic proof in the way as a brief explanation:
    (1) x= 0.999...
    (2) 10x= 9+x // 10x= 9.999...
    (3) 9x=9
    (4) x=1
    Ans: There is no axiom or theorem to prove (1) => (2).

    Note: If the steps of converting a number x to <fixed_point_number> is not
    finite, x is not a ratio of two integers, because the following
    statement is always true: ∀x,a∈ℚ, x-a∈ℚ

    ---End of quote

    What does the arity of the "n-ary <fixed_point_number>" refer to? The
    base or the number of digits?

    Any rational number can be represented with a single fractional digit
    when represented in the base of its denominator.

    I.e., 3/7 = 0.3 (base 7)

    And as far as I am aware, the rationality of a number does not depend on
    its representation...

    -Stefan
    --
    There is no such thing as luck. Luck is nothing but an absence of bad luck.
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Fri Mar 29 05:06:29 2024
    From Newsgroup: comp.lang.c++

    On Thu, 2024-03-28 at 21:33 +0100, Stefan Große Pawig wrote:
    wij <wyniijj5@gmail.com> writes:
    Snipet from https://sourceforge.net/projects/cscall/files/MisFiles/RealNumber-en.txt/download

    ...
    Real Nunmber(ℝ)::= {x| x is represented by n-ary <fixed_point_number>, the
       digits may be infinitely long }

       Note: This definition implies that repeating decimals are irrational number.
             Let's list a common magic proof in the way as a brief explanation:
               (1) x= 0.999...
               (2) 10x= 9+x  // 10x= 9.999...
               (3) 9x=9   
               (4) x=1
             Ans: There is no axiom or theorem to prove (1) => (2).

       Note: If the steps of converting a number x to <fixed_point_number> is not
             finite, x is not a ratio of two integers, because the following
             statement is always true: ∀x,a∈ℚ, x-a∈ℚ

    ---End of quote

    What does the arity of the "n-ary <fixed_point_number>" refer to? The
    base or the number of digits?

    Yes, base of the number system.
    Any rational number can be represented with a single fractional digit
    when represented in the base of its denominator.

    I.e., 3/7 = 0.3 (base 7)

    And as far as I am aware, the rationality of a number does not depend on
    its representation...

    Exactly.
    You quoted a slightly outdated text. Click the link above to see the most updated text.
    -Stefan

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Fri Mar 29 11:36:37 2024
    From Newsgroup: comp.lang.c++

    On 28/03/2024 19:25, wij wrote:
    On Thu, 2024-03-28 at 18:17 +0100, David Brown wrote:
    On 27/03/2024 22:39, wij wrote:
    On Wed, 2024-03-27 at 13:40 -0700, Chris M. Thomasson wrote:
    On 3/27/2024 9:05 AM, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational. >>>>>>>>>>
    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>>>> never terminates which means the conversion is never complete.




    You can stop iteration as soon as you detect a cycle, or period if you >>>> will. In 1/7, say it took 6 iterations to hit the period... Sound okay? >>>
    Stupid! It is an infinite string. Cycle or period can only be determined for
    finite string.


    Nonsense.

    You /know/ the cycle for the infinite decimal expansion for 1/7 - it is
    the digits "142857", repeated every 6 digits in the decimal expansion.
    Again, that's what the notation 0.(142857) - /your/ choice of notation,
    so presumably familiar to you - means.

    "0.(142857)" is pre-determined and specified not detected. (unless I misunderstood
    what Chris said)


    You are so confused that I would not be surprised if you misunderstood
    Chris. And Chris' posts score much higher on enthusiasm than on clarity.

    The fact that 1/7 has the decimal expansion 0.(142857) - that is, an
    unending repetition of the digits 142857 - is simple to calculate and
    easy to prove correct. It is "pre-determined" in the sense that it is
    the unique decimal expansion for 1/7. But I don't understand what you
    mean by "specified and not detected" - it is not something that Chris
    invented out of thin air.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Fri Mar 29 11:53:23 2024
    From Newsgroup: comp.lang.c++

    On 28/03/2024 19:23, wij wrote:
    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite >>>>> steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>> never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree
    you will not finish.  That does not mean it is not the decimal expansion
    of 1/7 - the list of multiples of (negative) powers of 10 which sum up
    to 1/7.  You just need a better notation so that you can finish the task
    - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even
    though you could not write it out long-hand, and you agree that 1/7 i
    rational.  And clearly 0.(142857) is a repeating decimal, since that's
    what the notation means.

    I can't see how you can still misunderstand this.


    You are restating your assertion without proof, again. I have provided mine. (If you say that is you proof, I will say it is invalid).



    There is no point in giving you a rigorous proof that 0.(142857) is the decimal expansion of 1/7, if that is what you are contesting. To be
    fully rigorous, it requires an understanding of the definition of the
    real numbers, sequence limits, and the meaning and validity of
    operations on infinite sequences. You have demonstrated that you don't understand any of that. You have learned a few of the terms, but failed
    to understand the concepts. Oh, and it also requires understanding what
    a proof is, which again is clearly outside your expertise.

    Ralf gave a proof earlier - it is still in the quoted material above.
    That is as good as we can get at your level of mathematical
    understanding. To be more rigorous, we would need to demonstrate that
    the manipulation (multiplication by a finite integer, and subtraction of sequences) of infinite decimal expansions is valid. That is all
    standard stuff, known to mathematics students the world over, but you
    are not nearly ready.

    You are going to have to go back-track a long way in what you think you
    know about mathematics. Somewhere along the line in your education,
    you've got things badly wrong. And instead of stopping up and trying to figure out why everyone else is saying something different from you, or
    asking your teachers for help, you have battered on with your mistakes, leading you to sillier and steadily less logical conclusions.

    I think mathematics is a great hobby. It's a shame to see someone spend
    their time and effort on doing it so badly.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Fri Mar 29 13:03:13 2024
    From Newsgroup: comp.lang.c++

    On 28/03/2024 20:41, Chris M. Thomasson wrote:
    On 3/28/2024 10:47 AM, David Brown wrote:
    On 27/03/2024 21:17, Chris M. Thomasson wrote:
    On 3/27/2024 3:31 AM, David Brown wrote:
    On 26/03/2024 21:13, Chris M. Thomasson wrote:
    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Obviously (to everyone except perhaps wij).

    ;^)


    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    That would not be a defined number.  I am not convinced it is
    meaningful to talk about its properties at all.


    Well, it would be a "number" at any finite view of it? Or, is that
    just moronic thinking?

    It is not a defined number in any way - you are explicitly using a
    procedure which does not give any defined or deterministic results.
    How could it be a number when no two people could agree to its value?

    Now, if you were to take a TRNG and generate a series of digits,
    writing each one down as you go along, then at any given time you
    would have a finite decimal expansion which would be a number (a
    rational, if that matters to you).  But that is a particular instance
    of creating such a number - the procedure you describe does not define
    a number nor is it a number in itself.

    Would it be fair to say it defines a random number that is an actual
    number at every finite step... Is that a stupid thought?


    It is not defining a number at all. It is defining a /procedure/ for generating different numbers.


    For some reason it makes me think of infinite convergents of
    continued fractions.

    I am not sure you are helping yourself or anyone else there.

    Well, shit happens. Just some fun with numbers? ;^)


    Fun is always good. And there's plenty of fun to be had with continued fractions - but pick sequences with a pattern, not random numbers.


    A sequence of digits obtained randomly does not converge.

    True, but at every "step", it can be a rational? I just think it can be
    a fun study, so to speak...


    Certainly random sequences can be interesting to study, though I prefer defined sequences. And certainly every finite sequence of digits is a rational. But your sequences of randomly generated digits don't
    converge. (What would they converge to?)


    Can we gain a rational that can approximate any irrational up to a
    certain precision, so to speak?

    Of course we can.  That is a completely separate issue.

    Yeah. Well, okay. I agree.


    If you have a real number "x" (positive for simplicity), and a
    precision "e", then we can easily find a rational number q such that
    |x - q| < e. We do so by letting "i" be an integer greater than 1/e.
    Let "j" be the first integer less than or equal to i * x.

    Using a TRNG to "generate" x, and a precision, say when we stop drawing digits from the TRNG, would create a rational. Right?


    Yes, but it is a different rational each time. You haven't defined a
    number. If you had defined a number, then you could calculate it to a
    given precision, and /I/ could calculate it to the same precision, and
    we'd each have the same result. That doesn't happen with random generators.


    So
         j <= (i * x) < (j + 1)

    and thus

         j / i <= x < (j + 1) / i

    q0 = j / i and q1 = (j + 1) / i are both rational numbers, and "x"
    lies between them.

    q1 - q0 = 1 / i, which is less than "e" since "i" is greater than 1/e.

    So since (q1 - q0) < e, and q0 <= x < q1, then we can see that "x" is
    "trapped" between two rationals that are both less than "e" from "x".

    You can approximate any real number as closely as you like with a
    series of rational numbers.  That is basically what it means to say
    that the real numbers "complete" the rationals - the fill in the gaps
    that can be expressed as the limits of bounded sequences of rationals
    where the limit is not itself a rational.

    Are you saying that a number constructed digit-by-digit using a TRNG is undefined? Its not a number, however it creates many numbers during the construction process? Fair enough?


    Any given finite sequence of digits taken from a TRNG will give you a
    rational number. But "take 20 digits from a TRNG" does not define a
    number - it defines a procedure for generating numbers. Do you see the difference?


    Ahhh shit, this is just me having some fun. Sorry.

    That's no problem. As long as you are trying to learn, and trying to
    have fun, it's fine by me.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Fri Mar 29 23:14:18 2024
    From Newsgroup: comp.lang.c++

    On Fri, 2024-03-29 at 11:53 +0100, David Brown wrote:
    On 28/03/2024 19:23, wij wrote:
    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
        
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
        

    Nonsense.
        

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure
    never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree you will not finish.  That does not mean it is not the decimal expansion of 1/7 - the list of multiples of (negative) powers of 10 which sum up
    to 1/7.  You just need a better notation so that you can finish the task - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even though you could not write it out long-hand, and you agree that 1/7 i rational.  And clearly 0.(142857) is a repeating decimal, since that's what the notation means.

    I can't see how you can still misunderstand this.


    You are restating your assertion without proof, again. I have provided mine.
    (If you say that is you proof, I will say it is invalid).



    There is no point in giving you a rigorous proof that 0.(142857) is the decimal expansion of 1/7, if that is what you are contesting.  To be
    fully rigorous, it requires an understanding of the definition of the
    real numbers, sequence limits, and the meaning and validity of
    operations on infinite sequences.  You have demonstrated that you don't understand any of that.  You have learned a few of the terms, but failed
    to understand the concepts.  Oh, and it also requires understanding what
    a proof is, which again is clearly outside your expertise.

    Ralf gave a proof earlier - it is still in the quoted material above.
    That is as good as we can get at your level of mathematical
    understanding.  To be more rigorous, we would need to demonstrate that
    the manipulation (multiplication by a finite integer, and subtraction of sequences) of infinite decimal expansions is valid.  That is all
    standard stuff, known to mathematics students the world over, but you
    are not nearly ready.

    You are going to have to go back-track a long way in what you think you
    know about mathematics.  Somewhere along the line in your education,
    you've got things badly wrong.  And instead of stopping up and trying to figure out why everyone else is saying something different from you, or asking your teachers for help, you have battered on with your mistakes, leading you to sillier and steadily less logical conclusions.

    I think mathematics is a great hobby.  It's a shame to see someone spend their time and effort on doing it so badly.

    Have you ever wondered why you cannot prove something you hold true for granted for so long?
    If you cannot provide a proof, what you said above only make you more a sinner. --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Fri Mar 29 16:48:06 2024
    From Newsgroup: comp.lang.c++

    On 29/03/2024 16:14, wij wrote:
    On Fri, 2024-03-29 at 11:53 +0100, David Brown wrote:
    On 28/03/2024 19:23, wij wrote:
    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational. >>>>>>>>>>
    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure >>>>> never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree >>>> you will not finish.  That does not mean it is not the decimal expansion >>>> of 1/7 - the list of multiples of (negative) powers of 10 which sum up >>>> to 1/7.  You just need a better notation so that you can finish the task >>>> - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even
    though you could not write it out long-hand, and you agree that 1/7 i
    rational.  And clearly 0.(142857) is a repeating decimal, since that's >>>> what the notation means.

    I can't see how you can still misunderstand this.


    You are restating your assertion without proof, again. I have provided mine.
    (If you say that is you proof, I will say it is invalid).



    There is no point in giving you a rigorous proof that 0.(142857) is the
    decimal expansion of 1/7, if that is what you are contesting.  To be
    fully rigorous, it requires an understanding of the definition of the
    real numbers, sequence limits, and the meaning and validity of
    operations on infinite sequences.  You have demonstrated that you don't
    understand any of that.  You have learned a few of the terms, but failed
    to understand the concepts.  Oh, and it also requires understanding what
    a proof is, which again is clearly outside your expertise.

    Ralf gave a proof earlier - it is still in the quoted material above.
    That is as good as we can get at your level of mathematical
    understanding.  To be more rigorous, we would need to demonstrate that
    the manipulation (multiplication by a finite integer, and subtraction of
    sequences) of infinite decimal expansions is valid.  That is all
    standard stuff, known to mathematics students the world over, but you
    are not nearly ready.

    You are going to have to go back-track a long way in what you think you
    know about mathematics.  Somewhere along the line in your education,
    you've got things badly wrong.  And instead of stopping up and trying to
    figure out why everyone else is saying something different from you, or
    asking your teachers for help, you have battered on with your mistakes,
    leading you to sillier and steadily less logical conclusions.

    I think mathematics is a great hobby.  It's a shame to see someone spend
    their time and effort on doing it so badly.


    Have you ever wondered why you cannot prove something you hold true for granted
    for so long?

    Yes, regularly. Sometimes I will then try to find a proof, or look up
    and learn about the proofs. Sometimes I will have to accept that
    proving the particular thing is beyond my mathematical skills, or my
    time and energy, or my interest, and I will defer to accepting that
    others have proven it.


    If you cannot provide a proof, what you said above only make you more a sinner.


    In this particular case, I most certainly /can/ provide a proof. But I
    can't provide a proof that /you/ would understand. And since writing a
    proof would be a fair effort, off-topic, and clearly a waste of time
    since you are impervious to mathematical reasoning, I will not bother.
    You can look up such proofs online - I'm sure there are countless
    Youtube videos that will explain it to anyone who is actually interested
    in learning and not merely trying to claim the whole world is wrong
    except them.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Sat Mar 30 00:16:27 2024
    From Newsgroup: comp.lang.c++

    On Fri, 2024-03-29 at 16:48 +0100, David Brown wrote:
    On 29/03/2024 16:14, wij wrote:
    On Fri, 2024-03-29 at 11:53 +0100, David Brown wrote:
    On 28/03/2024 19:23, wij wrote:
    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational.

    Nonsense.
         
    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)
         

    Nonsense.
         

    I am surprise your math. knowledge is so low worse than teenagers.

    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number?

    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure
    never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree
    you will not finish.  That does not mean it is not the decimal expansion
    of 1/7 - the list of multiples of (negative) powers of 10 which sum up
    to 1/7.  You just need a better notation so that you can finish the task
    - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even though you could not write it out long-hand, and you agree that 1/7 i rational.  And clearly 0.(142857) is a repeating decimal, since that's
    what the notation means.

    I can't see how you can still misunderstand this.


    You are restating your assertion without proof, again. I have provided mine.
    (If you say that is you proof, I will say it is invalid).



    There is no point in giving you a rigorous proof that 0.(142857) is the decimal expansion of 1/7, if that is what you are contesting.  To be fully rigorous, it requires an understanding of the definition of the real numbers, sequence limits, and the meaning and validity of
    operations on infinite sequences.  You have demonstrated that you don't understand any of that.  You have learned a few of the terms, but failed to understand the concepts.  Oh, and it also requires understanding what a proof is, which again is clearly outside your expertise.

    Ralf gave a proof earlier - it is still in the quoted material above. That is as good as we can get at your level of mathematical understanding.  To be more rigorous, we would need to demonstrate that the manipulation (multiplication by a finite integer, and subtraction of sequences) of infinite decimal expansions is valid.  That is all standard stuff, known to mathematics students the world over, but you
    are not nearly ready.

    You are going to have to go back-track a long way in what you think you know about mathematics.  Somewhere along the line in your education, you've got things badly wrong.  And instead of stopping up and trying to figure out why everyone else is saying something different from you, or asking your teachers for help, you have battered on with your mistakes, leading you to sillier and steadily less logical conclusions.

    I think mathematics is a great hobby.  It's a shame to see someone spend their time and effort on doing it so badly.


    Have you ever wondered why you cannot prove something you hold true for granted
    for so long?

    Yes, regularly.  Sometimes I will then try to find a proof, or look up
    and learn about the proofs.  Sometimes I will have to accept that
    proving the particular thing is beyond my mathematical skills, or my
    time and energy, or my interest, and I will defer to accepting that
    others have proven it.


    If you cannot provide a proof, what you said above only make you more a sinner.


    In this particular case, I most certainly /can/ provide a proof.  But I can't provide a proof that /you/ would understand.  And since writing a proof would be a fair effort, off-topic, and clearly a waste of time
    since you are impervious to mathematical reasoning, I will not bother.
    You can look up such proofs online - I'm sure there are countless
    Youtube videos that will explain it to anyone who is actually interested
    in learning and not merely trying to claim the whole world is wrong
    except them.

    Not the whole world, you can see some on the internet claiming "0.999...!=1", although the proof is also invalid. And, in every generation, every kid  (developed IQ) in school will keep wondering why 1/3=0.333... 'will stop' and why the the number very close to the left of 1 is not 0.999.... !
    Have you wondered if 1/3=0.333..., the conversion algorithm is theoretically flawed?
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Keith Thompson@Keith.S.Thompson+u@gmail.com to comp.lang.c++ on Fri Mar 29 11:35:28 2024
    From Newsgroup: comp.lang.c++

    David Brown <david.brown@hesbynett.no> writes:
    [...]
    I think mathematics is a great hobby. It's a shame to see someone
    spend their time and effort on doing it so badly.

    It's also a shame to see someone engaging here in a discussion that has
    nothing to do with C++. David, if you must feed this particular troll,
    I suggest doing so in comp.theory.

    *You don't have to reply to everything.*
    --
    Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
    Working, but not speaking, for Medtronic
    void Void(void) { Void(); } /* The recursive call of the void */
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Fri Mar 29 15:33:44 2024
    From Newsgroup: comp.lang.c++

    On 3/29/2024 5:03 AM, David Brown wrote:
    On 28/03/2024 20:41, Chris M. Thomasson wrote:
    [...]
    Are you saying that a number constructed digit-by-digit using a TRNG
    is undefined? Its not a number, however it creates many numbers during
    the construction process? Fair enough?


    Any given finite sequence of digits taken from a TRNG will give you a rational number.  But "take 20 digits from a TRNG" does not define a
    number - it defines a procedure for generating numbers.  Do you see the difference?

    Indeed I do.


    Ahhh shit, this is just me having some fun. Sorry.

    That's no problem.  As long as you are trying to learn, and trying to
    have fun, it's fine by me.

    :^)

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Fri Mar 29 15:40:44 2024
    From Newsgroup: comp.lang.c++

    On 3/29/2024 8:14 AM, wij wrote:
    [...]
    Have you ever wondered why you cannot prove something you hold true for granted
    for so long?

    If you cannot provide a proof, what you said above only make you more a sinner.

    Oh common. You know better. Well, at least I think you do.


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Chris M. Thomasson@chris.m.thomasson.1@gmail.com to comp.lang.c++ on Fri Mar 29 15:43:21 2024
    From Newsgroup: comp.lang.c++

    On 3/29/2024 9:16 AM, wij wrote:
    [...]
    Have you wondered if 1/3=0.333..., the conversion algorithm is theoretically flawed?

    Yawn.

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Sat Mar 30 15:44:35 2024
    From Newsgroup: comp.lang.c++

    On 29/03/2024 17:16, wij wrote:
    On Fri, 2024-03-29 at 16:48 +0100, David Brown wrote:
    On 29/03/2024 16:14, wij wrote:
    On Fri, 2024-03-29 at 11:53 +0100, David Brown wrote:
    On 28/03/2024 19:23, wij wrote:
    On Thu, 2024-03-28 at 18:16 +0100, David Brown wrote:
    On 27/03/2024 17:05, wij wrote:
    On Wed, 2024-03-27 at 16:02 +0100, David Brown wrote:
    On 27/03/2024 14:32, wij wrote:
    On Wed, 2024-03-27 at 13:57 +0100, Ralf Goertz wrote:
    Am Wed, 27 Mar 2024 20:12:38 +0800
    schrieb wij <wyniijj5@gmail.com>:

    On Wed, 2024-03-27 at 12:50 +0100, David Brown wrote:
    On 26/03/2024 22:43, wij wrote:

    Just repeat the pattern infinitely, then it is irrational. >>>>>>>>>>>>
    Nonsense.

    As said "∀x,a∈ℚ, x-a∈ℚ", if the subtraction a= 142857/10^(6*i)
    cannot terminate, 1/7 != 0.(142857)


    Nonsense.


    I am surprise your math. knowledge is so low worse than teenagers. >>>>>>>>>>
    Use the standard trick:

    x=0.[142857] => 1,000,000*x=142857.[142857]

    subtract the first equation from the second:

    999,999*x=142857 => x=142857/999,999=1/7


    To determine whether a number x is rational or not, we can repeatedly subtract
    rational numbers a? from x. If x-a1-a2-a3-...=0 can be verified in finite
    steps, then x is rational. Otherwise, x is irrational.
    If x is a repeating decimal, proposition "repeating decimal is rational" is
    simply false by sematics.


    Let me just ask you two simple questions:

    Do you think 1/7 is a rational number or an irrational number? >>>>>>>>
    rational

    What do you think the decimal expansion of 1/7 is?


    When converting 1/7 to decimal, the result ≒ 0.(142857), the procedure
    never terminates which means the conversion is never complete.


    It is a repeating decimal.  If you try to write it all out, then I agree
    you will not finish.  That does not mean it is not the decimal expansion
    of 1/7 - the list of multiples of (negative) powers of 10 which sum up >>>>>> to 1/7.  You just need a better notation so that you can finish the task
    - and 0.(142857), as you wrote, is one such notation.

    (I have no idea what you think the symbol "≒" might mean.)

    But you agree that 0.(142857) is the decimal expansion of 1/7, even >>>>>> though you could not write it out long-hand, and you agree that 1/7 i >>>>>> rational.  And clearly 0.(142857) is a repeating decimal, since that's >>>>>> what the notation means.

    I can't see how you can still misunderstand this.


    You are restating your assertion without proof, again. I have provided mine.
    (If you say that is you proof, I will say it is invalid).



    There is no point in giving you a rigorous proof that 0.(142857) is the >>>> decimal expansion of 1/7, if that is what you are contesting.  To be
    fully rigorous, it requires an understanding of the definition of the
    real numbers, sequence limits, and the meaning and validity of
    operations on infinite sequences.  You have demonstrated that you don't >>>> understand any of that.  You have learned a few of the terms, but failed >>>> to understand the concepts.  Oh, and it also requires understanding what >>>> a proof is, which again is clearly outside your expertise.

    Ralf gave a proof earlier - it is still in the quoted material above.
    That is as good as we can get at your level of mathematical
    understanding.  To be more rigorous, we would need to demonstrate that >>>> the manipulation (multiplication by a finite integer, and subtraction of >>>> sequences) of infinite decimal expansions is valid.  That is all
    standard stuff, known to mathematics students the world over, but you
    are not nearly ready.

    You are going to have to go back-track a long way in what you think you >>>> know about mathematics.  Somewhere along the line in your education,
    you've got things badly wrong.  And instead of stopping up and trying to >>>> figure out why everyone else is saying something different from you, or >>>> asking your teachers for help, you have battered on with your mistakes, >>>> leading you to sillier and steadily less logical conclusions.

    I think mathematics is a great hobby.  It's a shame to see someone spend >>>> their time and effort on doing it so badly.


    Have you ever wondered why you cannot prove something you hold true for granted
    for so long?

    Yes, regularly.  Sometimes I will then try to find a proof, or look up
    and learn about the proofs.  Sometimes I will have to accept that
    proving the particular thing is beyond my mathematical skills, or my
    time and energy, or my interest, and I will defer to accepting that
    others have proven it.


    If you cannot provide a proof, what you said above only make you more a sinner.


    In this particular case, I most certainly /can/ provide a proof.  But I
    can't provide a proof that /you/ would understand.  And since writing a
    proof would be a fair effort, off-topic, and clearly a waste of time
    since you are impervious to mathematical reasoning, I will not bother.
    You can look up such proofs online - I'm sure there are countless
    Youtube videos that will explain it to anyone who is actually interested
    in learning and not merely trying to claim the whole world is wrong
    except them.


    Not the whole world, you can see some on the internet claiming "0.999...!=1", although the proof is also invalid.

    Of course there are no valid proofs that 0.999... != 1, since it
    0.999... is equal to 1.

    But there are folks on the internet claiming the earth is flat, birds
    are not real, and every other bit of nonsense you could imagine.

    And, in every generation, every kid
    (developed IQ) in school will keep wondering why 1/3=0.333... 'will stop'

    I've never known anyone to wonder that - any kid who learns about this
    learns that it does /not/ stop. That's what the three dots mean. But
    maybe you didn't write quite what you meant to write here.

    and
    why the the number very close to the left of 1 is not 0.999.... !

    Certainly people wonder about things like this. They wonder if 0.999... really is the same as 1, and how could they prove it. (It /is/ the
    same, and the proof is easy.) They wonder if there is a number "just to
    the left of 1", and what it might be. (There is no such number.)

    /Wondering/ about these things, and being curious about them, is great. Claiming falsehoods about them, writing nonsense and calling it a
    "proof", is /not/ great.


    Have you wondered if 1/3=0.333..., the conversion algorithm is theoretically flawed?


    I have wondered about a lot of things, including things I know to be
    easily proven true - such as that 1/3 = 0.333... And I have challenged
    things like this, checked that /I/ can prove them true, or wondered if
    there were alternative definitions of real numbers, decimal
    representations, basic arithmetic, etc., in which the results are
    different. It turns out that if you want some useful fundamental
    properties to be true (such as reals being a complete ordered field),
    some results are inevitable. That is how you do mathematics.


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Sat Mar 30 15:49:16 2024
    From Newsgroup: comp.lang.c++

    On 29/03/2024 19:35, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    I think mathematics is a great hobby. It's a shame to see someone
    spend their time and effort on doing it so badly.

    It's also a shame to see someone engaging here in a discussion that has nothing to do with C++. David, if you must feed this particular troll,
    I suggest doing so in comp.theory.

    *You don't have to reply to everything.*


    It is Easter, and Usenet traffic is low. No, I don't have to reply to everything (and I don't - I have replied to very few of wij's broken
    maths threads), and this thread will soon die away. I am trying to get
    some idea of why wij thinks the way he does, and perhaps even help him
    think differently (though that's quite optimistic).

    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Sat Mar 30 23:14:14 2024
    From Newsgroup: comp.lang.c++

    On Sat, 2024-03-30 at 15:49 +0100, David Brown wrote:
    On 29/03/2024 19:35, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    I think mathematics is a great hobby.  It's a shame to see someone
    spend their time and effort on doing it so badly.

    It's also a shame to see someone engaging here in a discussion that has nothing to do with C++.  David, if you must feed this particular troll,
    I suggest doing so in comp.theory.

    *You don't have to reply to everything.*


    It is Easter, and Usenet traffic is low.  No, I don't have to reply to everything (and I don't - I have replied to very few of wij's broken
    maths threads), and this thread will soon die away.  I am trying to get some idea of why wij thinks the way he does, and perhaps even help him
    think differently (though that's quite optimistic).

    Persuade me and readers with proof, otherwise you lie or spread lies (from the moment)
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Sat Mar 30 19:26:35 2024
    From Newsgroup: comp.lang.c++

    On 30/03/2024 16:14, wij wrote:
    On Sat, 2024-03-30 at 15:49 +0100, David Brown wrote:
    On 29/03/2024 19:35, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    I think mathematics is a great hobby.  It's a shame to see someone
    spend their time and effort on doing it so badly.

    It's also a shame to see someone engaging here in a discussion that has
    nothing to do with C++.  David, if you must feed this particular troll, >>> I suggest doing so in comp.theory.

    *You don't have to reply to everything.*


    It is Easter, and Usenet traffic is low.  No, I don't have to reply to
    everything (and I don't - I have replied to very few of wij's broken
    maths threads), and this thread will soon die away.  I am trying to get
    some idea of why wij thinks the way he does, and perhaps even help him
    think differently (though that's quite optimistic).


    Persuade me and readers with proof, otherwise you lie or spread lies (from the moment)


    You were given a proof, but rejected it for no reason other than it
    showed that your jumble of claims was incorrect. Thus I don't think
    there is any point in trying to give more detailed proofs. But if you
    like, I can give some links to other people's proofs - starting with
    proving that 0.999... equals 1. If you agree with these, maybe we can
    move on to proving that 1/3 equals 0.33... repeating, and then further
    onto showing that repeating decimals are rational. So let me know which
    of these links you agree with, or disagree with (preferably with reasons
    or justification for disagreeing with them).

    <https://en.wikipedia.org/wiki/0.999...> <https://www.purplemath.com/modules/howcan1.htm> <https://brilliant.org/wiki/is-0999-equal-1/>


    (I don't need to persuade any other readers - they already know this stuff.)


    And if you think I am lying, you can add lying to your list of concepts
    that you don't understand.


    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From wij@wyniijj5@gmail.com to comp.lang.c++ on Sun Mar 31 03:30:21 2024
    From Newsgroup: comp.lang.c++

    On Sat, 2024-03-30 at 19:26 +0100, David Brown wrote:
    On 30/03/2024 16:14, wij wrote:
    On Sat, 2024-03-30 at 15:49 +0100, David Brown wrote:
    On 29/03/2024 19:35, Keith Thompson wrote:
    David Brown <david.brown@hesbynett.no> writes:
    [...]
    I think mathematics is a great hobby.  It's a shame to see someone spend their time and effort on doing it so badly.

    It's also a shame to see someone engaging here in a discussion that has nothing to do with C++.  David, if you must feed this particular troll,
    I suggest doing so in comp.theory.

    *You don't have to reply to everything.*


    It is Easter, and Usenet traffic is low.  No, I don't have to reply to everything (and I don't - I have replied to very few of wij's broken maths threads), and this thread will soon die away.  I am trying to get some idea of why wij thinks the way he does, and perhaps even help him think differently (though that's quite optimistic).


    Persuade me and readers with proof, otherwise you lie or spread lies (from the moment)


    You were given a proof, but rejected it for no reason other than it
    showed that your jumble of claims was incorrect.  Thus I don't think
    there is any point in trying to give more detailed proofs.  But if you like, I can give some links to other people's proofs - starting with
    proving that 0.999... equals 1.  If you agree with these, maybe we can
    move on to proving that 1/3 equals 0.33... repeating, and then further
    onto showing that repeating decimals are rational.  So let me know which
    of these links you agree with, or disagree with (preferably with reasons
    or justification for disagreeing with them).

    <https://en.wikipedia.org/wiki/0.999...> <https://www.purplemath.com/modules/howcan1.htm> <https://brilliant.org/wiki/is-0999-equal-1/>


    (I don't need to persuade any other readers - they already know this stuff.)


    And if you think I am lying, you can add lying to your list of concepts
    that you don't understand.


    I cannot read English fast. I will pick the one proof not in my proof. Archimedean property just states that infinitesmal does not exit, IIUC. It is an assertion, not a proof. But I think, if infinitesimal does not exit, what did
    those calculus pioneers baffled at?
    (I just have a thought, with Archimedean property, you cannot say "infinite repeating"
    because there is no 1/∞, this applies to the decimal representation of √2) The second one's proof depends on magic trick to make people believe, but neither a valid proof. I have shown how the magic works in my post.
    The third one's link, ... the same.
    You saw my Simple Enough Proof For Kids (kids know what the Emperor's Cloth is) and can't disprove it or prove your belief. What should I interpret if you attack too hard?
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From Tim Rentsch@tr.17687@z991.linuxsc.com to comp.lang.c++ on Thu Apr 25 16:33:50 2024
    From Newsgroup: comp.lang.c++

    Paavo Helde <eesnimi@osa.pri.ee> writes:

    27.03.2024 04:42 Chris M. Thomasson kirjutas:

    On 3/26/2024 2:51 PM, Paavo Helde wrote:

    26.03.2024 22:13 Chris M. Thomasson kirjutas:

    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Any number represented by stored digits on Earth has finite number
    of digits (because Earth is finite) and therefore is rational,
    regardless of how the digits are generated.

    Even with a TRNG?

    TRNG is defined as a device having access to a "physical entropy
    source". For producing an irrational number it ought to produce an
    infinite never-repeating sequence of digits.

    It's not clear if any physical mechanism would in principle produce a non-repeating infinite sequence of digits, the fact that the world is quantized might rather speak against it.

    The world being quantized is irrelevant. Flipping a coin has two
    "quantized" outcomes - either heads or tails. However, if the two
    outcomes are completely unpredictable then the coin can serve as a
    True random number generator. All that is known about quantum
    mechanics has found (as I understand it) that it is statistical
    only and completely unpredictable. And that property suffices
    to be a TRNG.

    Even if it did, the lifetime
    of a physical device is finite, so it can only produce a finite
    sequence of digits. Even if the lifetime of the hypothetical device
    would be infinite, we do not possess the infinite space and time to
    store the result. Such infinities are strictly the territory of
    mathematics, in real world we can have only finite sequence of digits.

    None of that matters. All that does matter is that if we know any
    finite number of outputs we still don't know anything about what the
    next output will be. There is no way to prove, in a mathematical
    sense, that a proposed TRNG is in fact a mathematically perfect
    TRNG. But we can make TRNGs in the sense that they have resisted
    all efforts to successfully predict their behavior (in a way that
    is statistically significant).

    If you want to represent irrational numbers you need to use some
    other encoding schema, e.g. "sqrt(2)" (8 bytes, voila!).

    pi? ;^D

    In mathematics, a notion like pi actually defines an irrational number
    by fixing its properties. For some such irrational numbers it is
    possible to give an infinite algorithm which produces the sequence of
    its digits. The funny thing is that after fixing the number there is
    no randomness any more, so e.g. a machine computing subsequent digits
    of pi would make a pretty poor RNG ;-)

    What you're saying about pi is true of any deterministic random
    number generator. Yet there are lots of deterministic RNG's that do
    a fine job of generating random numbers. I know of no mathematical
    result that says consecutive digits of pi would fail any of the many statistical tests for RNG's that have been devised. As long as the
    starting point is not known, AFAIAA there is no reason to think
    consecutive digits of pi would be any worse as a random number
    generator than any other deterministic random number generator.

    (Note: what I am calling deterministic random number generators
    are sometimes referred to as PRNGs, for "pseudo random number
    generators".)

    Incidentally, pi is not just irrational but transcendental. The
    property of being irrational is not by itself guarantee that a
    number would be a good source of random digits. Probably that
    statement is true for (arbitrary) transcendental numbers also.
    But pi is not just any transcendental number. :)
    --- Synchronet 3.20a-Linux NewsLink 1.114
  • From David Brown@david.brown@hesbynett.no to comp.lang.c++ on Fri Apr 26 12:46:49 2024
    From Newsgroup: comp.lang.c++

    On 26/04/2024 01:33, Tim Rentsch wrote:
    Paavo Helde <eesnimi@osa.pri.ee> writes:

    27.03.2024 04:42 Chris M. Thomasson kirjutas:

    On 3/26/2024 2:51 PM, Paavo Helde wrote:

    26.03.2024 22:13 Chris M. Thomasson kirjutas:

    On 3/26/2024 7:51 AM, wij wrote:
    [...]

    Repeating decimals are rational, say

    0.142857 142857 142857

    That is just 1 / 7 represented in base 10.

    Now, think of using a TRNG to create each digit...

    That would be, irrational... ;^)

    Any number represented by stored digits on Earth has finite number
    of digits (because Earth is finite) and therefore is rational,
    regardless of how the digits are generated.

    Even with a TRNG?

    TRNG is defined as a device having access to a "physical entropy
    source". For producing an irrational number it ought to produce an
    infinite never-repeating sequence of digits.

    It's not clear if any physical mechanism would in principle produce a
    non-repeating infinite sequence of digits, the fact that the world is
    quantized might rather speak against it.

    The world being quantized is irrelevant. Flipping a coin has two
    "quantized" outcomes - either heads or tails. However, if the two
    outcomes are completely unpredictable then the coin can serve as a
    True random number generator. All that is known about quantum
    mechanics has found (as I understand it) that it is statistical
    only and completely unpredictable. And that property suffices
    to be a TRNG.

    Yes, quantum effects are great for TRNG's. To have a RNG, you want two things: a known and consistent output distribution (it doesn't have to
    an even distribution, but you need to know it to compensate for it), and
    it needs to be non-deterministic - that is, you can't predict the next
    output from previous outputs or other information. If it would be theoretically possible to predict the output, it's a PRNG. If it is not possible even theoretically, it is a TRNG.


    Even if it did, the lifetime
    of a physical device is finite, so it can only produce a finite
    sequence of digits. Even if the lifetime of the hypothetical device
    would be infinite, we do not possess the infinite space and time to
    store the result. Such infinities are strictly the territory of
    mathematics, in real world we can have only finite sequence of digits.

    None of that matters. All that does matter is that if we know any
    finite number of outputs we still don't know anything about what the
    next output will be.

    Yes.

    There is no way to prove, in a mathematical
    sense, that a proposed TRNG is in fact a mathematically perfect
    TRNG.

    We can be sure that many types of TRNG are "true" random number
    generators in the "physics sense". That is not as strong as a
    "mathematical sense", in that the laws of physics are always open to improvement as we learn more about the universe. But things like
    thermal noise in electronics components is known - by current physics
    theory - to be truly random. (Measuring it disturbs things, unfortunately.)

    But we can make TRNGs in the sense that they have resisted
    all efforts to successfully predict their behavior (in a way that
    is statistically significant).


    Yes.

    If you want to represent irrational numbers you need to use some
    other encoding schema, e.g. "sqrt(2)" (8 bytes, voila!).

    pi? ;^D

    In mathematics, a notion like pi actually defines an irrational number
    by fixing its properties. For some such irrational numbers it is
    possible to give an infinite algorithm which produces the sequence of
    its digits. The funny thing is that after fixing the number there is
    no randomness any more, so e.g. a machine computing subsequent digits
    of pi would make a pretty poor RNG ;-)

    What you're saying about pi is true of any deterministic random
    number generator. Yet there are lots of deterministic RNG's that do
    a fine job of generating random numbers. I know of no mathematical
    result that says consecutive digits of pi would fail any of the many statistical tests for RNG's that have been devised. As long as the
    starting point is not known, AFAIAA there is no reason to think
    consecutive digits of pi would be any worse as a random number
    generator than any other deterministic random number generator.

    (Note: what I am calling deterministic random number generators
    are sometimes referred to as PRNGs, for "pseudo random number
    generators".)

    The key practical distinction, I think, is not whether or not the
    sequence is deterministic - but whether or not anyone can determine it.
    A "true" RNG is one where it is not physically feasible to determine
    future values in the sequence, but it does not matter whether that is
    because the values are inherently random (such as quantum noise), or if
    it is simply impossible to determine them (perhaps because the
    calculations take too much time and energy).

    Regarding things like statistical random number tests, any test carried
    out will be done over a finite sample of the data. A given RNG may pass
    such tests and then later exhibit patterns such as repetition - there is
    no way to determine this. (And a practical TRNG is a RNG that will pass
    any such tests of any length that can be achieved.)

    The digits of the decimal expansion of pi will (I believe) pass any statistical test. But it will not pass a determinism test targeting pi.


    Incidentally, pi is not just irrational but transcendental. The
    property of being irrational is not by itself guarantee that a
    number would be a good source of random digits. Probably that
    statement is true for (arbitrary) transcendental numbers also.
    But pi is not just any transcendental number. :)

    Neither the irrational nor transcendental properties are sufficient.
    (They are not even necessary, in practical terms - it doesn't even
    matter if a sequence repeats as long as it does not repeat during the
    digits you are using.)

    Liouville's constant, the sum of 10 ^ (-n!) for n = 1 to infinity, was
    the first number proven to be transcendental. But since it is almost
    entirely zeros, it would not make a useful random number source.

    For theoretically infinite sequences, you want a normal number (or at
    least, normal in a given base) - that is, one for which the probability
    of seeing any given sequence of base b digits of length n gets
    asymptotically closer to b ^ -n. I.e., all sequences are equally
    likely, over time.







    --- Synchronet 3.20a-Linux NewsLink 1.114