RE: Slow Gradient Method.

From: "Niclas Jonsson" <Niclas.Jonsson@farmbio.uu.se> Subject: RE: Slow Gradient Method. Date: Thu, 31 May 2001 09:31:36 +0200 I don't know if the SLOW method uses numerical derivatives or not but it is perhaps important to point out that the SLOW option on the $ESTIMATION is not the same as the NUMERICAL option. The NUMERICAL option requests that the second derivatives for the LAPLACE method are computed numerically, which, I presume, is quicker and sometimes more tractable than analytical second derivatives. As I recall it, the SLOW option gives you the version of FOCE that was implemented in NONMEM IV. In one of the beta versions of NONMEM V there was an improvement to the FOCE algorithm that made it about three times faster (my own, hardly remebered, benchmarks). The new method could, however, not handle certain cases, i.e. CENTERing, mixture model and when the NUMERICAL option is used. Niclas