[MITgcm-devel] mom_calc_ke

[Martin Losch]

Hi Jean-Michel,
why do you want to split it? To have different loop boundaries for the first part, like this:
      DO j=1-Oly,sNy+Oly-1
       DO i=1-Olx,sNx+Olx-1
or even
      DO j=1-Oly,sNy+Oly
       DO i=1-Olx,sNx+Olx
? I can do that along with my change.

Martin

On Jul 18, 2012, at 11:36 PM, Jean-Michel Campin wrote:

> Hi Martin,
> 
> I think it's better to have .GT.0. rather than .NE.0. anyway,
> so if it helps with your compiler optimisation problem,
> you should go and change it.
> 
> I also had in mind (for a long time) to split this bottom-drag
> computation loop in (at least) 2 parts (linear & quadratic) but
> no urgent need to do it now.
> 
> Cheers,
> Jean-Michel
> 
> On Wed, Jul 18, 2012 at 09:14:33PM +0200, Martin Losch wrote:
>> Hi there, I stumbled across a situation, where the optimization of ifort (-O3) destroys the code and leads to NaNs. The problem is (probably) due to the optimzed code not producing small negative numbers in S/R mom_calc_ke for KE (kinetic energy). In mom_?_bottomdrag, we have SQRT(KE) and this results in NaNs in some cases. The problem can be fixed, when the if-statement in mom_?_bottomdrag (line 91 for u and 97 for v) is changed from .NE. 0. to .GT. 0.
>> 
>> What do you think? is this worth it?
>> 
>> Martin
>> 
>> 
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