On Fri, 20 Jul 2007, John Gehman wrote: [usefulness of sigma]
> For the case where all data has the same error, as yours appears to, > then all data is weighted equally. HOWEVER, this value does scale the > residual and the sensitivity of the gradients, and I believe > therefore does influence convergence. It may not make that big a > difference in the regime where you are working, but I have noticed > before with some of my applications that it was important to be > realistic about the error. OK, I thoughts so. Effectively, it allows the fitter to get it slightly wrong before cranking up the error. Is there a way to supply a custom error function (e.g. via a callback) to the fitter in GSL? > I'm not sure whether a gsl_vector_scale after the fact > would be more efficient that explicit divisions during the loop? I'm not sure, but I think that would produce a different result... Gordan _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
