llfunc <- function (x) { -sum(dweibull(AM,shape=exp(x[1]),scale=exp(x[2]), log=TRUE))}
Have you tried this? If no, I suspect the warnings will disappear when you try this. If not, I suggest you rewrite "llfunc" to store "nlglk <- (-sum(...))" and then print out x whenever nlglk is NA or Inf or Nan.
hope this helps. spencer graves
Eric Rescorla wrote:
I'm trying to fit a Weibull distribution to some data via maximum likelihood estimation. I'm following the procedure described by Doug Bates in his "Using Open Source Software to Teach Mathematical Statistics" but I keep getting warnings about NaNs being converted to maximum positive value:
llfunc <- function (x) { -sum(dweibull(AM,shape=x[1],scale=x[2], log=TRUE))}Warning messages: 1: NaNs produced in: dweibull(x, shape, scale, log) 2: NA/Inf replaced by maximum positive value 3: NaNs produced in: dweibull(x, shape, scale, log) 4: NA/Inf replaced by maximum positive value
mle <- nlm(llfunc,c(shape=1.5,scale=40), hessian=TRUE)
Can someone offer some advice here?
Thanks, -Ekr
-- [Eric Rescorla [EMAIL PROTECTED] http://www.rtfm.com/
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