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NaN with -ffast-math #174
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May I ask, which input file were you using? Test1? |
The input file attached to the report: "media_bug.txt" GitHub does not allow .egsinp extensions. |
Ahhh sorry it threw me not being an egsinp. |
Is this still a problem on the current develop branch? I could not reproduce on centos. Thanks! |
Which gcc did you test with? I thought this was a 4.4 series issue.
… On Jan 23, 2017, at 12:57 PM, Reid Townson ***@***.***> wrote:
Is this still a problem on the current develop branch? I could not reproduce on centos. Thanks!
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Good point - I was on gcc 4.8.5. |
Suggestion: discard the -ffast-math flag. Better (i.e., faster and less dangerous) outcomes with modern gcc versions are achieved using -march=native -mtune=native |
Will do, thanks for the info! |
NaN (still) shows up when using -ffast-math with the Fortran compiler. This happens with gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC).
Sample input file for
tutor7pp
below.With -ffast-math flag:
Medium 1 sige = 1.00000000362749373E-015 NaN monotone = T T
Medium 2 sige = 1.00000000362749373E-015 NaN monotone = T T
Without -ffast-math:
Medium 1 sige = 0.43671621424277174 0.43386623396694124 monotone = T T
Medium 2 sige = 0.24630246820211257 0.24325696800012028 monotone = T T
As far as I know, this does not produce any significant differences in the results of
tutor7pp
(or any other code), but I'm not entirely sure.material.txt
media_bug.txt
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