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From: Richard <rgrdev_@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Request for source code review of simple Ising model
Date: Sat, 19 Apr 2014 14:55:27 +0100
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Udyant Wig <udyantw@gmail.com> writes:

> Keith Thompson <kst-u@mib.org> writes:
> | I think I've seen PRNGs where the low-order bit actually alternates 0,
> | 1, 0, 1, 0, 1, ..., but the sample implementation in the standard
> | doesn't do that.
>
>  There is a discussion of this very issue (or something extremely close
>  to it) in one of the assignments of Steve Summit's (fine) online C
>  programming classes found here:
>
>  http://www.eskimo.com/~scs/cclass/cclass.html
>
>  It is Exercise 8 of the third assignment:
>
>  http://www.eskimo.com/~scs/cclass/asgn.beg/PS3.html
>
>  The explanation is here in the answers section:
>
>  http://www.eskimo.com/~scs/cclass/asgn.beg/PS3a.html
>
> | Here's a test program if anyone wants to try it.  If it prints either
> | "01010101..." or "10101010...", please let us know what implementation
> | you're using.
> |
> | #include <stdio.h>
> | #include <stdlib.h>
> |
> | int main(void) {
> |     for (int i = 0; i < 64; i ++) {
> |         printf("%d", rand() % 2);
> |     }
> |     putchar('\n');
> | }
>
>  I changed it thusly to calm gcc down:
>
> #include <stdio.h>
> #include <stdlib.h>
>
> int main(void) {
>     int i;
>     for (i = 0; i < 64; i ++) {
>         printf("%d", rand() % 2);
>     }
>     putchar('\n');
>
>     return 0;
> }
>
> 1011110011010110000010110001111000111010111101001010100100011101
>
> | On one of my systems, the output is
>>
> | 1011110011010110000010110001111000111010111101001010100100011101
>
>  The two outputs are equal.  Independent confirmations by Emacs Lisp,
>
> (string-equal
>  "1011110011010110000010110001111000111010111101001010100100011101"
>  "1011110011010110000010110001111000111010111101001010100100011101")
> => t
>
>  and their MD5 sums,
>
> $ md5sum # Keith Thompson's output
> 1011110011010110000010110001111000111010111101001010100100011101
> 89e91cff9eefca6a24afaee2809c0859  -
>
> $ md5sum # Udyant Wig's output
> 1011110011010110000010110001111000111010111101001010100100011101
> 89e91cff9eefca6a24afaee2809c0859  -
>
>  verify this.
>

Serious Q : are you taking the piss?

-- 
"Avoid hyperbole at all costs, its the most destructive argument on
the planet" - Mark McIntyre in comp.lang.c