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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