Hello,
I'm using the following for loop to find regression curves using a list of
functions (formList), a list of starting
values (startList), uppervalues (upperList) and lower values (lowerList).
A sample of the list of function I use in the loop is the following:
FormList <- list(PTG.P ~ fz1(Portata, a, b), PTG.P ~ fz2(Portata, a, b), PTG.P
~ fz3(Portata,a, b, d, e),
PTG.P ~ fz4(Portata, a, b), PTG.P ~ fz5(Portata, a, b, d), PO4.P ~ fz1(Portata,
a, b),
PO4.P ~ fz2(Portata, a, b), ...
And the loop I use is:
resultList <- list()
for (i in 1:length(formList))
{
resultList[[i]] <- nls(formList[[i]], data=subset(dati, Fiume=="Laveggio"),
start=startList[[i]],
nls.control(maxiter=1000, warnOnly=TRUE), algorithm='port',
na.action=na.omit,lower=lowerList[[i]],
upper=upperList[[i]])
}
When the computation ends I get 5 warning messages (one of false convergence, 4
of singular convergence:
In nls(formList[[i]], data = subset(dati, Fiume == "Laveggio"), : Convergence
failure: false convergence (8)
2: In nls(formList[[i]], data = subset(dati, Fiume == "Laveggio"), :
Convergence failure: singular convergence (7)
If I want to get the summary of the first object of the resultList I do:
summary(resultList[[1]])
And I get a result with no problem:
Formula: PTG.P ~ fz1(Portata, a, b)
Parameters:
Estimate Std. Error t value Pr(>|t|)
a 61.158 18.591 3.290 0.00140 **
b 7.616 8.720 0.873 0.38464
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
Residual standard error: 91.32 on 96 degrees of freedom
Algorithm "port", convergence message: both X-convergence and relative
convergence (5)
It also works if I try to get the summary of the first 5 object of the
resultList with:
summaryList<-list()
for (i in 1:5)
{
summaryList[[i]]<-summary(resultList[[i]])
}
But if I try to get the summary of all the objects of the resultList (there are
35 objects) it doesn't work...
I tried:
summaryList<-list()
> for (i in 1:length(resultList))
+ {
+ summaryList[[i]]<-summary(resultList[[i]])
+ }
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
Does somebody have an idea on how to fix this?
Thanks
Laura
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