Curve fit: "No constraints active or violated"

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Wed, 03/18/2015 - 08:55 am

Dear Igor users, I have a question about curve fitting with constraints. I have this message but I don't find this meaning in the book:
Fit converged properly
--Curve fit with constraints--
<b>No constraints active or violated<b>
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Thanks for your help.
Sébastien
It means that the fit you did uses constraints, but the coefficients that were arrived at as the solution are within the constraint boundaries. If a coefficient winds up at the constraint boundary, then the constraint is "active" meaning that the value is a consequence of its having been constrained, and is not the the optimal value. If a coefficient winds up outside the constraint boundary, then it "violates" the constraint. This should only happen when you have two constraints and they conflict.

There is one case in which you might do a fit with constraints without knowing that you did it: the Gauss2D built-in fit function applies a constraint to the "cor" coefficient to keep it within the -1 to 1 range for which it is defined.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

March 18, 2015 at 09:40 am - Permalink