[FLASH-USERS] Big Problem??

Tomasz Plewa tplewa at fsu.edu
Wed Jul 30 08:31:46 EDT 2008


Seyit -

Neither of -r8, -i4, -I, or -c option has much to do with optimizations. 
Please take a look into compiler manual pages.

I noticed the difference in formatting the output, which is 
inconsequential for your problem and likely reflects a difference in 
implementation of Fortran standard.

At the moment I do not see any strong evidence that there is a serious 
problem with either the code or your computer systems. I believe you can 
do some good science with it.

Tomek
--
Seyit Hocuk wrote:
> Tomek,
>
> I tried using only " -c -r8 -i4 -I $(MPI_PATH)/include " optimizations 
> on all with single proc, single refinement level. The differences are 
> still there. Including  -I $(MPI_PATH)/include has no effect (though 
> pc 1 does not work without it). Is this still agressive optimization? 
> I always need -c otherwise I get errors compiling. I need -r8 
> otherwise while running I get errors. I guess i4 in not so necessary, 
> but I thought it wouldn't hurt. It also makes no difference by the way 
> in my simulations.
>
> Oh and the differences in calculations of k, kJ, c0, omega ... etc. is 
> purely precision. Pc 1 and pc 3 have same values, but pc 2 has one 
> more digit to them.
>
>
> Tomasz Plewa wrote:
>> Seyit -
>>
>> The "problem" is already present in a serial model.
>>
>> Also, I noticed that you are using very aggressive compiler 
>> optimizations. This frequently affects floating point accuracy. Can 
>> you produce a single processor, single patch models with no 
>> optimizations?
>>
>> Tomek
>> -- 
>
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