[R] problem in using optim

Ravi Varadhan rvaradhan at jhmi.edu
Fri May 7 15:12:21 CEST 2010

It probably means that your parameters are taking on values that are
infeasible.  You may have to impose constraints on your parameters to get a
solution (e.g. bounds constraints). If you need better help, you have to
send us a minimal, self-contained, reproducible example.


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Carol Gao
Sent: Friday, May 07, 2010 5:53 AM
To: R-help at r-project.org
Subject: [R] problem in using optim

Dear R users,

When I was trying to use the function *optim* to get the MLEs, quite a few
warning messages showed up as below:

Warning in log(psi * lam) : NaNs produced

I am just wondering what does this mean? Was it something wrong with my
likelihood function or was it sth wrong with the data?

Thanks in advance.

Carol Gao

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