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MathGroup Archive 2004

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Re: NonlinearFit not reaching convergence, even after spoon-feeding it with initial parameters.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg45898] Re: NonlinearFit not reaching convergence, even after spoon-feeding it with initial parameters.
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Thu, 29 Jan 2004 05:34:46 -0500 (EST)
  • Organization: The University of Western Australia
  • References: <bv835f$iab$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <bv835f$iab$1 at smc.vnet.net>,
 gilmar.rodriguez at nwfwmd.state.fl.us (Gilmar Rodr?guez Pierluissi) 
 wrote:

> My questions are:
> (1.) How can I control the NUMBER OF ITERATIONS in NonlinearFit?
> (2.) How can I control the STEPSIZE in NonlinearFit?
> (3.) How can I control the TOLERANCE in NonlinearFit?
> (4.) Notice that I "spoon fed" NonlinearFit the above initial
> parameters (which I know work fine), and I still
> get a warning message!  How can I remedy this situation?

I suggest that you look up the documentation for FindFit instead (which 
NonlinearFit uses in 5.0).

Since your data is experimental you cannot eliminate the accuracy 
warning message unless you reduce the AccuracyGoal.

See http://physics.uwa.edu.au/pub/Mathematica/MathGroup/NonlinearFitting.nb
for some more comments on your problem.

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 9380 2734
School of Physics, M013                         Fax: +61 8 9380 1014
The University of Western Australia      (CRICOS Provider No 00126G)         
35 Stirling Highway
Crawley WA 6009                      mailto:paul at physics.uwa.edu.au 
AUSTRALIA                            http://physics.uwa.edu.au/~paul


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