Message-ID: <481700F1.7030500@med.ucm.es>
Date: 2008-04-29T11:05:21Z
From: Stephan Moratti
Subject: nlme optim control option
In-Reply-To: <mailman.3.1209463201.10911.r-sig-mixed-models@r-project.org>
Hello,
I am using the nlme package for quite a while, but recently I have
discovered the "optim" option in the lmeControl function and I have read
that until the R verison 2.2.0 the optimization function is "nlminb" and
before it was "optim" by default. As I am a "user" of R I am not into
the optimization functions. However, I have a case now where with optim
= "nlminb" the model does not converge, whereas with optim = "optim" the
model converges.
Can somebody explain to me in easy words what the difference is ? If
nlminb does not converge, but optim does, is the result less trustable ?
Thanks,
Stephan
--
*Stephan Moratti, PhD/
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