[MITgcm-support] IEEE_INVALID_FLAG and IEEE_OVERFLOW_FLAG

[Martin Losch]

Yangxin,

you need to figure out, where the overflow is happening before you can decide what to do. If you are using gfortran, this link might help:
https://stackoverflow.com/questions/29823099/debugging-with-gdb-and-gfortran-fpes

basically you need to add compiler flags that help you find the problem, recompile and run again, possibly with a debugger.

Martin


> On 13. Nov 2017, at 18:43, Yangxin He <y67he at uwaterloo.ca> wrote:
> 
> Hey,
> 
> I am sending a mode-one oceanic IW from the left boundary using obcs, and there is a sponge layer on the right boundary.
> 
> If I set delta x to be 300m, it runs alright. But I want better resolution, so I set delta x to be 200m. Now no matter what deltaT it is, for example, I tried deltaT ranging from 0.5 to 100, it gives me the message,
> 
> "Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_OVERFLOW_FLAG
> STOP NORMAL END".
> 
> And my output files are filled up with NaNs.
> I also checked my stdout file to see the CFL condition,
> "
> (PID.TID 0000.0001) %MON trAdv_CFL_u_max              =   1.5873708813573E-02
> (PID.TID 0000.0001) %MON trAdv_CFL_v_max              =   0.0000000000000E+00
> (PID.TID 0000.0001) %MON trAdv_CFL_w_max              =   0.0000000000000E+00
> (PID.TID 0000.0001) %MON advcfl_uvel_max              =   1.6143191354999E-02
> (PID.TID 0000.0001) %MON advcfl_vvel_max              =   0.0000000000000E+00
> (PID.TID 0000.0001) %MON advcfl_wvel_max              =   0.0000000000000E+00
> (PID.TID 0000.0001) %MON advcfl_W_hf_max              =   0.0000000000000E+00
> "
> So it seems the CFL condition is fine?
> Part of my data file is as the following:
> "
> # Time stepping parameters
>  &PARM03
>  nIter0=0,
>  nTimeSteps=500,
>  deltaT=10.,
>  abEps=0.1,
>  pChkptFreq=0.,
>  chkptFreq=0.,
>  dumpFreq=50000.,
>  monitorFreq=2500.,
>  monitorSelect=2,
>  &
> 
> # Gridding parameters
>  &PARM04
>  usingCartesianGrid=.TRUE.,
>  delX=200*200.,
>  delY=5.E3,
>  delZ=40*5.,
> &
> "
> What can be the problem? How can I fix it?
> 
> Thanks
> Yangxin
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