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Nonlinear Least Squares Fitting
- From: Andreas Gros <agros at rz dot uni-osnabrueck dot de>
- To: gsl-discuss at sources dot redhat dot com
- Date: Tue, 20 Nov 2001 09:58:02 +0100
- Subject: Nonlinear Least Squares Fitting
Hello,
I'd like to submit a "bug" in the solver:
gsl_multifit_fdfsolver_lmsder.
In the section "Providing the function to be minimized" where the
function gsl_multifit_function_fdf is described, you mention the
function f that should store the distance between the values
calculated by the algorithm and the provided values.
As I tested the algorithm I've found, that this distance is not taken
as a "square", instead the algebraic sign of the distance seems to be
of some importance. My results were quite different, whenever I took
(y[i]-Yi) instead of (Yi-y[i]) (as it is shown in the example).
Taking the latter the solver works fine, taking the first distance the
results have been quite funny.
Andreas Gros
Andreas Gros, Tel.: 0179-1062416
Lotter Str. 99, 49078 Osnabrück
Amalienstr. 8, 97072 Würzburg
http://www.gros-webdesign.de