[R] summary of a list

Dieter Menne dieter.menne at menne-biomed.de
Tue Feb 10 18:10:33 CET 2009

lauramorgana <at> bluewin.ch <lauramorgana <at> bluewin.ch> writes:

> Hello,
> I'm using the following for loop to find regression curves using a list of
functions (formList), a list of

.. long non-reproducible code removed

> And I got the following error message:
> Error in chol2inv(object$m$Rmat()) : l'elemento (3, 3) è zero, quindi
l'inversa non può essere calcolata
> Which translated should be: Error in chol2inv(object$m$Rmat()): the element
(3, 3) is zero (NULL?),
> that's why the 
> inverse (inverse function?) can not be computed 

nls is rather nasty or nice in telling you when the result should not 
be trusted. Other software gives nonsense result without blinking.

In package nlme, there is a function nlsList which does directly what you
want, but there is little help besides revising the model for the cases
without convergence. 

Also try check Gabor Grothendieks package "nls2" which could help you 
finding better start values.


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