Hello,
Try the following.
fit <- nls(log(proc) ~ k + a*exp(b*cls), data = bline, start = c(k = 1,
a = 1, b = 1))
summary(fit)
plot(fitted(fit), log(bline$proc)) # Seems nice
Hope this helps,
Rui Barradas
Em 23-04-2013 13:05, catalin roibu escreveu:
Hello all!
I have a problem to use a biexponential regression model:
I use this code:
n3<-nls(proc~SSbiexp(cls,a,b,c,d),data=bline) and this is the error message:
Error in nls(y ~ cbind(exp(-exp(lrc1) * x), exp(-exp(lrc2) * x)), data =
xy, :
singular gradient
My data is like this:
structure(list(proc = c(387.177462830167, 508.090511433077,
321.836817656365,
151.226805860727, 150.885315536942, 86.2895998400175, 56.3215592398958,
39.5044440630984, 25.5703078997907, 7.33494872198676), cls = c(0.25,
0.5, 0.75, 1, 1.5, 2, 2.5, 3, 3.5, 4)), .Names = c("proc", "cls"
), row.names = c("0.25", "0.5", "0.75", "1", "1.5", "2", "2.5",
"3", "3.5", "4"), class = "data.frame")
Thank you!
______________________________________________
R-help@r-project.org 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.
