[MITgcm-support] optim_m1qn3: maximum iterations reached?

[Daniel Goldberg]

Hi Martin

I am using optim_m1qn3 (installed from your github repo).

I have been using it in optimisations with data.optim parameters as follows:


 &OPTIM

 optimcycle=0,

 numiter=1000,

 nfunc=10,

 dfminfrac=0.001,

 iprint=10,

 nupdate=5,

 /


and am seeing the optimisation terminate with omode=5 after about 100 iterations. The manual for m1qn3 suggests the maximum number of simulations has been reached, which is a lot less than numiter*nfunc, which (according to the git readme) is the max number of simulations. (Though i do note that "nsim" in the text output from the optim_m1qn3 executable changes at some point in the optimisation from its initial value of 10000.)

I then ran the optimisation again with nfunc=20 to see what would happen -- this time there is a termination with omode=4, the maximum number of iterations being reached -- this happened at optimcycle=116. Here, i notice that each subsequent optimcycle gives omode=1 in the optim_m1qn3 output -- im not sure if this is significant.

I was wondering if this behaviour makes sense to you, and if you would be able to explain it? Happy to provide more output from optim_m1qn3 (from the more recent optimisation with nfunc=20; the previous nfunc=10 output is deleted).

Many thanks
Dan

--
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Daniel Goldberg, PhD
Reader in Glaciology
School of Geosciences, University of Edinburgh
Geography Building, Drummond Street, Edinburgh EH8 9XP


em: dan.goldberg at ed.ac.uk<mailto:dan.goldberg at ed.ac.uk>
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The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.
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