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Problem with fitting

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  • Subject: [mg101336] Problem with fitting
  • From: Chris Schreiber <christian-schreiber at>
  • Date: Wed, 1 Jul 2009 06:37:27 -0400 (EDT)

Hi there,

I encounter the following problem when fitting a complicated function using FindFit: when running 

BBWorigin = 
 FindFit[Data2, {CHFSorigin[x] /. ABWorigin /. ABW /. BBW   /. CBW /. 
     DBW /. FGW} ,  {{COorigin, 4.3}}, {x}, MaxIterations -> 1000]

where I previously defined the function CHFSorigin and where the rules ABWorigin, ABW, BBW, CBW, DBW and FGW were also defined, I obtain the following output by mathematica:

{COorigin -> 4.3}
FindFit::fmgz: Encountered a gradient that is effectively zero. The \
result returned may not be a minimum; it may be a maximum or a saddle \
point. >>

My first reaction was to change COorigin to a different value, but that did not change the result, i.e. the fit always stopped at the initial value. Does anybody have 
any ideas about how to progress from here?

Best wishes, and thanks a lot,


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