From: Christfried Kunath <mailpuls_at_gmx.net>

Date: Tue 21 Jun 2005 - 19:57:39 EST

Date: Tue 21 Jun 2005 - 19:57:39 EST

Hello,

i have a problem with the function nls().

The algorithm "plinear" give me following error:

phi function(x,y) {

k.nls<-nls(y~1/(a*(x^2)+b*x+c),start=c(a=0.0005,b=0.02,c=1.5),alg="plinear")

Error in qr.solve(QR.B, cc) : singular matrix `a' in solve

I have found in the mailinglist

"https://stat.ethz.ch/pipermail/r-help/2001-July/012196.html" that is if t
he data are artificial. But the data are from my measurment.

The commercial software "Origin V.6.1" solved this problem with the Levenberg-Marquardt algorithm how i want. The reference results are: a = 9.6899E-6, b = 0.00689, c = 2.72982

What are the right way or algorithm for me to solve this problem and what means this error with alg="plinear"?

Thanks in advance.

-- Weitersagen: GMX DSL-Flatrates mit Tempo-Garantie! Ab 4,99 Euro/Monat: http://www.gmx.net/de/go/dsl ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Tue Jun 21 20:03:20 2005

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