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Re: nonlinearmodelfit problem

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  • Subject: [mg126105] Re: nonlinearmodelfit problem
  • From: "Dan O'Brien" <danobrie at>
  • Date: Wed, 18 Apr 2012 03:52:30 -0400 (EDT)
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  • References: <jm4vr2$2j0$> <>

I have had the same sort of problems.  How have you set up your 
simultaneous fit?  If it is set up so that your data is in the form


where the first index is for the dataset (1 or 2)
and your function is set up with kroneckerdelta


Then you could use the Weights option in NonlinearModelFit

Weights->(If[#1==2,100000,1]&) (if the larger ranged dataset is dataset 1)


On 4/17/2012 5:02 AM, M.Roellig wrote:
> On Thursday, April 12, 2012 12:16:02 AM UTC+2, L. Mattera wrote:
>> Hi
>> my name is Lorenzo Mattera, I am using since a short time Mathematica.
>> I am trying to solve a fitting problem where two sets of data have to be
>> fitted by two models depending on the same parameters.
>> I found very helpful the suggestions reported at
>> (and
>> references therein) so that I was able to
>> produce a working procedure. However, I have a "small" problem:
>> the two set of data have quite different weights as one is in the
>> 0-100000 range while the other is in the 0-1 range so that one of the two is
>> irrelevant in the fitting procedure.
>> It seems to me that NonlinearModelFit minimizes the sum of the squared
>> residuals,
>> any way to minimize the squared  normalized residuals?
>> Perhaps is one of the options, but so far I could not find it.
>> Tank you for the help
>> best regards
>> L. Mattera
> Hi,
> you could try to fit in the logarithmic domain.
> Markus

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