Re: Request for source code review of simple Ising model

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From	Ike Naar <ike@iceland.freeshell.org>
Newsgroups	comp.lang.c
Subject	Re: Request for source code review of simple Ising model
Date	Sun, 20 Apr 2014 10:10:23 +0000 (UTC)
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On 2014-04-20, Keith Thompson <kst-u@mib.org> wrote:
> Keith Thompson <kst-u@mib.org> writes:
>> Ike Naar <ike@iceland.freeshell.org> writes:
>>> On 2014-04-18, Keith Thompson <kst-u@mib.org> wrote:
>>>> 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');
>>>> }
>>>>
>>>> On one of my systems, the output is
>>>>
>>>> 1011110011010110000010110001111000111010111101001010100100011101
>>>
>>> Here it prints
>>>
>>> 0101010101010101010101010101010101010101010101010101010101010101
>>>
>>> The implementation is gcc version 4.5.3 (NetBSD nb2 20110806).
>>
>> Fascinating.  So there *are* modern implementations that have this
>> problem.
>>
>> The relevant implementation is the C standard library, not the compiler.
>> BSD has its own C standard library implementation.  I wonder if Mac OSX
>> (which is based on BSD) has this problem.
>>
>> The man page
>>     http://netbsd.gw.com/cgi-bin/man-cgi?rand+3+NetBSD-current
>> doesn't mention this, apart from the NAME section:
>>
>>     rand, srand, rand_r -- bad random number generator
>
> I've grabbed a copy of source code for the NetBSD libc implementation of
> rand() and run the same test on it on some of my own systems (64-bit
> Linux Mint 14, 32-bit Ubuntu 12.10ish, and Cygwin on Windows 7), and I
> *didn't* see alternating 0 and 1 low-order bits.  I even examined all
> available versions from the NetBSD CVS repository (the history goes back
> to 1993), and I see no differences in the available history that would
> explain this behavior.  Obviously I'm missing something.
>
> Ike: What is "NetBSD nb2 20110806"?  The latest release of NetBSD is
> 6.1.4; how does it relate to that?

$ uname -a
NetBSD iceland 6.1_STABLE NetBSD 6.1_STABLE (SDF6.amd64) #0: Tue Nov 26 12:49:14 UTC 2013  root@bjork:/spare/netbsd/src/sys/arch/amd64/compile/SDF6.amd64 amd64

Thread

Request for source code review of simple Ising model Udyant Wig <udyant@panda.goosenet.in> - 2014-04-10 23:38 +0530
  Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-10 13:30 -0700
    Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-12 00:34 +0530
      Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-11 12:25 -0700
      Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-16 01:12 +0530
        Re: Request for source code review of simple Ising model Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-16 01:33 +0100
          Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-16 17:57 +0530
            Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-16 06:00 -0700
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-16 10:58 -0400
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-16 09:07 -0700
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-16 12:22 -0400
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-16 10:38 -0700
                Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-16 19:37 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 12:00 +0530
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-17 09:32 +0000
                Re: Request for source code review of simple Ising model "BartC" <bc@freeuk.com> - 2014-04-17 12:24 +0100
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:16 -0700
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-17 04:41 -0700
                Re: Request for source code review of simple Ising model Les Cargill <lcargill99@comcast.com> - 2014-04-17 07:49 -0500
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:00 -0700
                Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-17 15:06 +0000
                Re: Request for source code review of simple Ising model Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 21:04 -0700
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-17 18:38 +0000
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 15:26 -0400
                Re: Request for source code review of simple Ising model "BartC" <bc@freeuk.com> - 2014-04-17 21:00 +0100
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 16:34 -0400
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-18 04:31 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 14:05 -0700
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 17:06 -0700
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-18 04:54 +0000
                Re: Request for source code review of simple Ising model Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-18 11:51 -0700
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 11:42 +0530
            Re: Request for source code review of simple Ising model Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-04-16 16:54 +0100
              Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-16 15:22 -0700
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-17 13:03 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-17 08:44 -0700
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 12:12 -0400
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 12:38 +0530
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-18 03:11 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 12:32 +0530
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 10:05 -0400
        Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-16 07:10 +0000
        Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-17 13:10 -0400
          Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 18:24 +0530
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 09:52 -0400
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 20:04 +0530
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 11:00 -0400
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 01:49 +0530
                Re: Request for source code review of simple Ising model glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-19 21:20 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:11 +0530
                Re: Request for source code review of simple Ising model Richard Damon <Richard@Damon-Family.org> - 2014-04-20 09:06 -0400
                Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-20 10:50 -0400
                Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-21 09:14 -0700
              Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-19 05:43 +0000
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 19:47 +0530
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 01:21 +0530
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 14:24 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 10:40 +0530
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 12:29 +0530
          Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 08:36 -0700
            Re: Request for source code review of simple Ising model James Kuyper <jameskuyper@verizon.net> - 2014-04-18 13:40 -0400
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 11:14 -0700
              Re: Request for source code review of simple Ising model Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-18 13:55 -0700
            Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 01:25 +0530
              Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 01:44 +0530
              Re: Request for source code review of simple Ising model Kaz Kylheku <kaz@kylheku.com> - 2014-04-18 20:24 +0000
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-18 13:36 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-19 20:18 +0530
              Re: Request for source code review of simple Ising model Richard <rgrdev_@gmail.com> - 2014-04-19 14:55 +0100
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 02:10 +0530
            Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-19 05:40 +0000
              Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 14:39 -0700
                Re: Request for source code review of simple Ising model Ian Collins <ian-news@hotmail.com> - 2014-04-20 10:44 +1200
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 17:11 -0700
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:24 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-19 17:19 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-20 10:10 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 14:21 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-20 22:18 +0000
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-20 19:27 -0700
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-21 12:38 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 18:12 +0530
                Re: Request for source code review of simple Ising model Ike Naar <ike@iceland.freeshell.org> - 2014-04-21 13:13 +0000
                Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-21 19:46 +0530
                Re: Request for source code review of simple Ising model Keith Thompson <kst-u@mib.org> - 2014-04-21 09:06 -0700
                Re: Request for source code review of simple Ising model jacob navia <jacob@spamsink.net> - 2014-04-21 00:26 +0200
        Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-18 01:15 +0530
        Re: Request for source code review of simple Ising model Udyant Wig <udyantw@gmail.com> - 2014-04-20 11:46 +0530

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