[R] nls vs nlme: parameter constraints
Manuel Morales
Manuel.A.Morales at williams.edu
Mon Jun 22 23:50:08 CEST 2009
Hello list,
I'm trying to fit a model like beta[trt]/(1+alpha*x) where the data
include some grouping factor. The problem is that the estimate for alpha
is undefined for some of the treatments - any value greater than 20 is
equally good and a step function would suffice. Ignoring the grouping
structure, I can fit this using nls with the port algorithm by
restricting the upper value of alpha to 20. Is there a way to do
something similar in nlme?
Thanks!
Manuel
--
http://mutualism.williams.edu
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