[mesa-users] variability in runs

[andres suarez]

Thanks for the advice Bill.
For the time being I took the shortest solution: since my runs were not
really long, I used only one thread, as Richard suggested, and get the same
behaviour in different runs.
I'd like to help in the debugging process; as you may have noticed already,
there is slight variability since the very first model, using the inlist I
previously attached, making me believe that the variability comes from a
propagation of this small differences. After your comments, I guess the
problem is then in the linear algebra solver, but I don't really know where
to follow up.
Regards,
a.



>
>
> On Wed, Apr 25, 2012 at 12:07 PM, Bill Paxton <paxton at kitp.ucsb.edu>wrote:
>
>>
>> On Apr 23, 2012, at 12:11 PM, andres suarez wrote:
>>
>> > I am running mesa version 3851 on a linux platform on an x86_64
>> multi-processor computer, using ifort.
>> >
>>
>> Hi Andres,
>>
>> I've worked on your problem some -- no solution as yet, but a couple of
>> options to get around it.
>>
>> I don't see the variability with gfortran, so the easiest work-around is
>> to switch to it (consider using the mesa SDK).
>>
>> If you are a die-hard ifort fan, you can avoid the bug by using the
>> slower banded lapack option for doing the linear algebra in star instead of
>> the default faster option that uses multicore parallelism.    To do this,
>> add these to &controls in your inlist:
>>
>>         small_mtx_decsol = 'lapack'
>>         large_mtx_decsol = 'lapack'
>>
>> We'll of course let you know if we can find a better solution.  Hopefully
>> it is a bug in my code rather than a compiler bug in ifort, but so far I
>> haven't been able to find it.  Help in debugging is welcome!!!!
>>
>> -Bill
>>
>>
>>
>>
>>
>
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