[S] NLMIN

Shuying Yang (spaksyy@iop.bpmf.ac.uk)
Tue, 10 Nov 1998 13:31:13 +0000


Hello everybody,

(1) I am using splus for windows nlmin function to minimize a non-linear
function. I then realised that nlminb does such kind of work as well, can
anyone tell me which one is better?
(2) Can anyone explain the "init.step " option in nlmin, it says in the
manual that this would dramatically effect the performance of the
optimizer? How to set up init.step to improve the optimizer?
(3) When nlmin is used, is there anyway to record for each parameter the
small but large enough step (h) in order to compute numerically the
approximation of Hessian Matrix?

Your help are very much appreciated.

Shuying Yang

Dr. Shuying Yang
Department of Biostatistics and Computing
Institute of Psychiatry
Kings College of London
London SE5 8AF
Tel: 0171-919-3840
Email: spaksyy@iop.bpmf.ac.uk

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