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mitscherlich
2009 Mar 12
3
avoiding termination of nls given convergence failure
...r regression to
a series of data sets using nls and the port algorithm from within a loop.
The general structure of the loop is:
for(i in 1:n){
… extract relevant vectors of dependent and independent variables …
… estimate starting values for Amax and Q.LCP…
fit<-nls(photosynthesis~fit.Mitcherlich(irradiance,Amax,LCP,Q.LCP),data=temp
,
start=list(Amax=Astart,Q.LCP=x,LCP=33),control=list(maxiter=100,tol=5e-4),
na.action=na.omit,trace=T,algorithm="port",lower=c(0,0,0))
…
}
Despite trying to estimate good starting values, the nls function
occasionally experiences...