Subject: Re: CCL:least squares fit

From: <[email-masked]>
Date: Thu, 23 Mar 1995 11:01:32 EDT

Hi,

    There are many ways (and there is more to it than just this) but 
the simplest way to get what you want is to just replace your 
parameter a by another parameter a^2 in your model.

    BTW, Marquardt-type algorithms are _bound_ to fail to converge 
in many cases - so beware.  The best is to use a _real_ nonlinear 
optimization code.

>  Dear netters,
>I am trying to do a non linear least squares fit, 
>using a Marquardt type algoritm, but I need to restrict some
>parameters to make my function behaves correctly.
>Is available any program to constrain parameters to be positive?
>

Best Regards,

W. R. Smith                        Professor
                                   Dept. of Mathematics and Statistics
                                   and School of Engineering 
                                   University of Guelph
FAX: 519-837-0221                  Guelph, Ontario
Tel: 519-824-4120, ext. 3038       CANADA N1G 2W1