[Users] Difference in NaN checks results of GRHydro

Hee Il Kim heeilkim at gmail.com
Sun Jul 18 20:16:47 CDT 2010


Hi,

Recently, I found the nancheks of GRHydro show different results sometimes
depending on the compilers and codes. As far as I've tested, nans appear
only if I use the private thorn GRHydro_RNSID (just a clone of Whisky_RNSID)
with XL compilers on AIX machines. I don't see any nans with Intel compilers
for the same parfile. Also old Whisky with BSSN_MoL passes the nanchecks
safely.

The difference happens actually for somewhat specific situations. It only
happens for differentially rotating stars. It disappears if I take a smaller
# of refinement levels.

I've tested it applying the IEEE strict floating point options to both
compilers (Intel and XL), but the results were same.

Since the problem doesn't happen for Whisky+BSSN_MoL, I think it is not the
problem of the private thorn only. My GRHydro_RNSID is basically the same
with Whisky_RNSID. Assuming most of you are using the similar thorn, I
attached the thornlist and the parfile. I hope you can examine and fix the
problem.

Regards,

Hee Il
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