[MITgcm-devel] Fwd: [MITgcm-cvs] MITgcm/pkg/seaice CVS Commit

[Martin Losch]

Hi,

this recent change in seaice_lsr.F (replace 1/SEAICE_deltaTdyn wiht precomputed recip_deltaT) changes some results at truncation level, also for adjoint and tlm. For the adm and tlm seaice_dynmix experiment, however, the FD gradients are, totally unexpectly, broken (only 2 digits remain and the comparision to the adjoint and tlm gradients are 2 orders of magnitude less accurate). Since the adjoint and tangent-linear gradients only change a little (11 digits of agreement remain, so that I get a “pass"), and the cost function is also not affected as much, I am a little at loss, what may cause this.

What should I do?
1. revert to old code: go back to 1/SEAICE_deltaTdyn instead of recip_deltaT
2. update all but the seaice_dynmix experiment
3. update all experiments and worry about the accuracy later?

Martin

> Begin forwarded message:
> 
> From: Martin Losch <mlosch at forge.csail.mit.edu>
> Subject: [MITgcm-cvs] MITgcm/pkg/seaice CVS Commit
> Date: 20 Jan 2016 15:02:53 CET
> To: <mitgcm-cvs at mitgcm.org>
> Reply-To: <MITgcm-cvs at mitgcm.org>
> 
> Update of /u/gcmpack/MITgcm/pkg/seaice
> In directory forge:/tmp/cvs-serv1185/pkg/seaice
> 
> Modified Files:
> 	seaice_lsr.F 
> Log Message:
> replace 1./SEAICE_deltaTdyn with recip_deltaT for better vectorisation
> affects some experiments at truncation level
> 
> 
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