R-beta: nonlinear fitting

Bill Simpson (wsimpson@uwinnipeg.ca)
Thu, 12 Mar 1998 09:36:15 -0600 (CST)


Date: Thu, 12 Mar 1998 09:36:15 -0600 (CST)
From: Bill Simpson <wsimpson@uwinnipeg.ca>
To: r-help <r-help@stat.math.ethz.ch>
Subject: R-beta: nonlinear fitting

Thanks very much Douglas for the pointer to nlm.
Maybe the "Notes on R" maintainer can add at least a mention of nlm in the
section on nonlinear fitting?

I never did nonlinear fitting in S-Plus before, so I have nothing to
unlearn, but I was hoping someone could show me how to do a least squares
fit with nlm.

example:
x<-c(1,2,3,4,5,6)
y<-.3*x^-.6 +.2
y<-y+rnorm(6,0,.01)

Please show me how to fit the model
y=a*x^b + c
by least squares.  I would like parameter estimates plus the standard
error for each param.

(This example could replace the current nonlinear fitting section in
"Notes on R")

Thanks very much for any help!

Bill Simpson

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