first of all I'd like to thank you for the quick help on my last which() problem.
Here is another one I could not tackle: I have data on an absorption measurement which I want to fit with an voigt profile:
fn.1 <- function(p){
for (i1 in ilong){
ff <- f[i1]
ex[i1] <- exp(S*n*L*voigt(u,v,ff,p[1],p[2],p[3])[[1]])
}
sum((t-ex)^2)
}
out <- nlm(fn.1, p = c(fo, GG, GL), hessian = TRUE, steptol = 1e-5, iterlim = 1000)
foN <- out$estimate[1]
GGN <- out$estimate[2]
GLN <- out$estimate[3]
This works fine but the my start value of S is to poor,
so I like to fit S in a second run, with the initial values from the first run
(two runs because I know that S as an parameter is an problem):
fn.2 <- function(p){
for (i1 in ilong){
ex[i1] <- exp(p[1]*n*L*voigt(u,v,f[i1],p[2],p[3],GLN)[[1]])
}
sum((t-ex)^2)
}
out <-nlm(fn.2, p = c(S,foN,GGN), hessian = TRUE,
steptol = 1e-5, iterlim = 1000,print.level=2)
SN <- out$estimate[1]The problem is now that the first value from nlm() is positive (1E-6 !?) and this leeds to an Inf:
iteration = 0 Step: [1] 0 0 0 Parameter: [1] -3.800000e-19 2.196660e+03 5.211179e-03 Function Value [1] 0.5890603 Gradient: [1] Inf 11.23381 -23.61961 -
Error in nlm(fn.2, p = c(S, foN, GGN), hessian = TRUE, steptol = 1e-5, : non-finite value supplied by nlm In addition: Warning message: NA/Inf replaced by maximum positive value
The number of parameters plays no role; same behaviour with p = c(S,GGN)
Can someone give a broad hint
Thomas______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
