[R] help with nls and Hill equation

Daniel Lakeland dlakelan at street-artists.org
Tue Oct 16 19:41:35 CEST 2007

On Tue, Oct 16, 2007 at 10:29:17AM -0400, Lanre Okusanya wrote:
> Thanks.
> I am just not used to having such a huge difference when changing the
> initial condition by 1 point. it usually tends to be an issue when you
> are way off (especially since the hill converged at 1.69). Does it
> have something to do with the algorithm or is the hill just very
> finicky?

Convergence of general nonlinear optimization problems is often
finicky, being wrong by a large amount in the right direction can
produce convergence, while a small amount in the wrong direction
causes divergence... These things almost always benefit from trying
various starting points, and from doing some analysis to determine a
good range of starting points.

Daniel Lakeland
dlakelan at street-artists.org

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