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Groups > comp.lang.c > #43096

Re: Request for source code review of simple Ising model

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: Request for source code review of simple Ising model
Date 2014-04-18 13:36 -0700
Organization None to speak of
Message-ID <lnppke4bp5.fsf@nuthaus.mib.org> (permalink)
References (2 earlier) <87wqev6631.fsf@panda.goosenet.in> <87a9bm5qhb.fsf@panda.goosenet.in> <53500B1E.5050404@verizon.net> <lnoazy645u.fsf@nuthaus.mib.org> <87bnvymmz6.fsf@panda.goosenet.in>

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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

That merely asserts that:

    In particular, it's not uncommon for the rand funciton to produce
    alternately even and odd numbers, such that if you repeatedly
    compute rand % 2, you'll get the decidedly non-random sequence 0,
    1, 0, 1, 0, 1, 0, 1... .

I'm looking for concrete examples of real-world implementations that
behave this way.

> | Here's a test program if anyone wants to try it.
[...]
> |     for (int i = 0; i < 64; i ++) {
[...]
>
>  I changed it thusly to calm gcc down:
>  
[...]
>     int i;
>     for (i = 0; i < 64; i ++) {
[...]

Compiling with "-std=c99" also works.

It's a pity that gcc rejects this particular C99 feature by default.
Even if the gcc maintainers don't feel they're ready to make C99 the
default standard, they could easily treat this as a GNU extension on top
of C90.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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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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