[R] None of pweibull/dweibull in the derivatives table?

[C. Joseph Lu]

Dear friends in R-world,

It seems like there is none of pweibull/dweibull (and other distribution
functions)
available in the derivatives table.

What I want to do is to feed both gradient and hessian into nlm()
on calculating MLE of Weibull distribution (with censored data),
however, I just can't get gradient by deriv() in R
(not even bother to mention hessian).

In Venables & Ripley's MASS book, this was (mine is 2nd ed., sorry)
discussed with deriv3(), however,
the formation of deriv3 differs from R's deriv.

Best regards,

C. Joseph Lu
Department of Statistics
National Cheng-Kung University
Tainan, Taiwan

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