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Re: Problem with fitting

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  • Subject: [mg101551] Re: Problem with fitting
  • From: dh <dh at>
  • Date: Fri, 10 Jul 2009 06:42:43 -0400 (EDT)
  • References: <h2fe8l$pvp$>

Hi Chris,

it looks like your expression does not depend on the parameter.

Try e.g.:

FindFit[Table[i, {i, 8}], x, {{a, 3}}, x]

and you get the message you describe.


Chris Schreiber wrote:

> 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,


> Christian


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