[MITgcm-devel] mom_calc_ke

[Jean-Michel Campin]

Hi Martin,

Was not thinking of loop boundary but to same computation when
quadratic drag is off. But I can do this later (need to check
how to write this to please TAF). And might be good also to
check-in your fix first (in case mine does not go well).

Cheers,
Jean-Michel

On Thu, Jul 19, 2012 at 10:47:24AM +0200, Martin Losch wrote:
> 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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