Hello Liang,
Besides looking at ?optim, you may also want to look into this nice
working example www.mayin.org/ajayshah/KB/R/documents/mle/mle.html
Regards,
Francisco
Francisco J. Zagmutt
Vose Consulting
1643 Spruce St., Boulder
Boulder, CO, 80302
USA
www.voseconsulting.com
Liang Wang wrote:
Hi, dear R users
I am a newbie in R and I need to use the method of meximum likelihood to fit a Weibull
distribution to my survival data. I use "optim" as follows:
optim(c(1.14,0.25),weibull.like,mydata=mydata,method="L-BFGS-B",hessian = TRUE)
My question is: how do I setup the constraints that the two parametrs of
Weibull to be pisotive?
Many thanks! Any comments are greatly appreciated!
Steven
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