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D.gnu - std.math.pow produces incorrect results when used with std.parallelism

reply "finalpatch" <fengli gmail.com> writes:
the following code compiled with GDC shows the bug
(I'm using the gcc 4.8 windows mingw32 version from 
https://bitbucket.org/goshawk/gdc/downloads)

import std.math;
import std.stdio;
import std.range;
import std.parallelism;

void main()
{
     enum n = 1000;
     float step = 1.0f/n;

     float[n] results_singlethreaded;
     float[n] results_multithreaded;

     foreach(i; iota(n))
         results_singlethreaded[i] = pow(step * i, 0.4545f);
     foreach(i; parallel(iota(n)))
         results_multithreaded[i] = pow(step * i, 0.4545f);
     foreach(i; iota(n))
         assert(results_singlethreaded[i] == 
results_multithreaded[i]);
}

~/Desktop $ ./test.exe
core.exception.AssertError test.d(26): Assertion failure

The same code passes without assertion when compiled with DMD.
Jun 01 2013
next sibling parent Johannes Pfau <nospam example.com> writes:
Am Sun, 02 Jun 2013 07:17:12 +0200
schrieb "finalpatch" <fengli gmail.com>:

 the following code compiled with GDC shows the bug
 (I'm using the gcc 4.8 windows mingw32 version from 
 https://bitbucket.org/goshawk/gdc/downloads)
 
 import std.math;
 import std.stdio;
 import std.range;
 import std.parallelism;
 
 void main()
 {
      enum n = 1000;
      float step = 1.0f/n;
 
      float[n] results_singlethreaded;
      float[n] results_multithreaded;
 
      foreach(i; iota(n))
          results_singlethreaded[i] = pow(step * i, 0.4545f);
      foreach(i; parallel(iota(n)))
          results_multithreaded[i] = pow(step * i, 0.4545f);
      foreach(i; iota(n))
          assert(results_singlethreaded[i] == 
 results_multithreaded[i]);
 }
 
 ~/Desktop $ ./test.exe
 core.exception.AssertError test.d(26): Assertion failure
 
 The same code passes without assertion when compiled with DMD.

Please file a bug report on bugzilla.gdcproject.org I can't reproduce this on linux/posix. Could you use feqrel to check the number of equal bits of the single/multithreaded results?
Jun 02 2013
prev sibling parent "finalpatch" <fengli gmail.com> writes:
Bug reported as #58
http://bugzilla.gdcproject.org/show_bug.cgi?id=58
I have added the output from feqrel to the report.

On Sunday, 2 June 2013 at 08:28:42 UTC, Johannes Pfau wrote:
 
 The same code passes without assertion when compiled with DMD.

Please file a bug report on bugzilla.gdcproject.org I can't reproduce this on linux/posix. Could you use feqrel to check the number of equal bits of the single/multithreaded results?

Jun 02 2013