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NNTP-Posting-Date: Tue, 13 Dec 2016 15:02:15 -0600
From: Gareth Owen <gwowen@gmail.com>
Newsgroups: comp.lang.c,comp.programming
Subject: Re: Fake random numbers? Bad programmers?
References: <o2jiap$oo0$1@dont-email.me> <o2piel$adq$6@dont-email.me>
Date: Tue, 13 Dec 2016 21:02:06 +0000
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Ken Brody <kenbrody@spamcop.net> writes:

> On 12/11/2016 7:56 AM, Mr. Man-wai Chang wrote:
>>
>> How to determine whether a random number generator is fake?
>>
>> How to determine whether a random number generator is cheating?
> [...]
>
> I would think that, since a "true" random number generator can
> generate any sequence of numbers (even the same number multiple times
> in a row), I'm not sure you could prove "badness" here.
>
> Reminds me of this:
>
>     http://xkcd.com/221/

Because "true" random number generators pass certain statistical tests
with probability close-enough-to-one as to make no matter.

"So, if it is impossible to definitively prove randomness, what can we
 do instead? The pragmatic approach is to take many sequences of random
 numbers from a given generator and subject them to a battery of
 statistical tests. As the sequences pass more of the tests, the
 confidence in the randomness of the numbers increases and so does the
 confidence in the generator" -- https://www.random.org/analysis/