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From: "John D'Errico" <woodchips@rochester.rr.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: solution of a transcendental equation
Date: Wed, 16 Jan 2008 18:59:01 +0000 (UTC)
Organization: John D'Errico (1-3LEW5R)
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Fulya <fulya_bagci@yahoo.com> wrote in message 
<22495104.1200504568448.JavaMail.jakarta@nitrogen.mathforum.org>...
> OK. I used 'fsolve'.

Fsolve is inappropriate to solve a least squares
problem as you are doing.

 
> I do least squares fitting of this function.It gives such an error and although 
the fit is good when I enter good initial parameters, it is not smooth and it 
gives what I write as the initial parameters.Error:
> 
> Conditioning of Gradient Poor - Switching To LM method

This is not an error message. It is a statement
about the algorithm's progress.


> Optimization terminated: search direction less than TolX.

This is not an error message. It is a statement
that the algorithm has finished its work.



> my code is
> .
> funi = @(y) mean(abs(y-a.*abs(Fsat+K.*y.*x)./ (Fsat+K.*x)).^(1-1./K));
> %yd is experimental y, yi is the theoretical y
> yi  = fsolve(funi,yd);
> .
> val = yd - yi


What are you solving for? y? Or are you
trying to solve for the parameters Fsat, K, a?

 John