Dear all I have got some problems with a least-squares regression using the function nls.
I want to estimate h, k and X of the following formula by using nls : exp(2*200*(q^2-4*h/k-0.25+(2/k-0.5+4*h^2/k^2)*log(abs((k*q^2+2*h*q-1)/(0.25*k-h-1)))))/((-k*q^2-2*h*q+1)*X) y as defined by c(0.009747 0.001949 0.000000 0.003899 0.000000 0.000000 0.005848 0.001949) q as defined by c(-0.7500 -0.6875 -0.5625 -0.4875 -0.4625 -0.4375 -0.4125 -0.3875) (length of the real q and y is 46; too long to post them here) i tought the correct using of nls would be: Mic<-nls(y~"function", start = list(k=1.0,h=0.1,X=exp(10)) But it doesn`t work. i tryed an easier formula like : Mic<-nls(y~h*exp(2*k*200*(q^2)), start=list(h=0.1,k=1,X=100000)) The result was the same. Isn`t "nls" the function i should use to solve this regression problem? Which things did i make wrong? Thank you very much in advance Michael _________________________________________________________________________ In 5 Schritten zur eigenen Homepage. Jetzt Domain sichern und gestalten! ______________________________________________ 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.html and provide commented, minimal, self-contained, reproducible code.