[R] Non linear regression with 2 explanatory variables

[Gavin Simpson]

hits=-2.6 tests=BAYES_00
X-USF-Spam-Flag: NO

On Wed, 2008-01-16 at 11:02 +0100, Janice Kielbassa wrote:
> Hello!
> 
> I want to do a non-linear regression with 2 explanatory variables 
> (something like : length ~ a * time * exp( b* temperature)), having a 
> data set (length, time, temperature). Which function could I use (I 
> tried nls but I think it doesn't work)

Janice, I'll start by saying I can't help you as I have never used nls()
myself and I am not familiar with this type of analysis.

Why do you think that nls() "doesn't work"? It is a widely used part of
R and thus probably very well tested.

My understanding of these things is that nls is a sophisticated tool
that requires some effort on the part of the user, such as selecting
appropriate starting values.

You are unlikely to get any further assistance from the list unless you
read the posting guide and post an example of what you did (preferably
with the actual data or dummy data with the same properties if not) and
the exact error message or output from R that lead you to believe that
nls() did not work.

HTH

G

> Thanks a lot!
> 
> Janice
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
-- 
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
 Dr. Gavin Simpson             [t] +44 (0)20 7679 0522
 ECRC, UCL Geography,          [f] +44 (0)20 7679 0565
 Pearson Building,             [e] gavin.simpsonATNOSPAMucl.ac.uk
 Gower Street, London          [w] http://www.ucl.ac.uk/~ucfagls/
 UK. WC1E 6BT.                 [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%