Thanks, I'll check lmdif.
As far as implementing the interface for reading
the covariance matrix / jacobian, it would be a very welcome addition. Afterall,
fitting parameters of a model function is a common task in experimental
data analysis, and it is instrumental to know the fitted errors and the
correlation between the fitted parameters.
Stanislaw Szpala, Ph.D.
100 Perth Drive
London Ontario N6A 5K8, Canada