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MathGroup Archive 2004

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Re: Using NDSolve in NonlinearFit

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48797] Re: Using NDSolve in NonlinearFit
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig-de>
  • Date: Wed, 16 Jun 2004 07:48:59 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <cap36v$c82$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

what is with:
fun[omega_?NumericQ, x_?NumericQ] :=
Module[{t, sol},
  sol = NDSolve[
            {y1'[t] == y2[t],
             y2'[t] == -omega^2*y1[t],

              y1[0] == 0, y2[0] == omega},

{y1[t], y2[t]},
{t, 0, x}];
y1[t] /. sol[[1]] /. t -> x
]

data = Table[{x, Sin[2*x]}, {x, 0, 2Pi, 2Pi/256}];

FindFit[data, fun[omega, x], {{omega, 2.2}}, x]

Regards
  Jens


"Dr. Ernst H.K. Stelzer" <stelzer at embl-heidelberg.de> schrieb im Newsbeitrag
news:cap36v$c82$1 at smc.vnet.net...
> Hi,
>
> I have been trying to use NDSolve inside various Fitting routines
> (NonlinearFit, FindFit, ...).  Although the NDSolve works fine both inside
> and outside a Module wrapper once inside a "fit"-function the variables
are
> never resolved.  At least the Print inside the function returns names
rather
> than numbers??
>
> What is my mistake?
> Has anybody solved this problem differently?
>
> I do not wish to write a new Fit-function and search myslef if it can be
> avoided.  The text below is copied as CellFormat and can be inserted and
> interpreted in any Mathematica Notebook.
>
> Sincerely
>
>        Ernst
>
> --------------------------------------------------------------------
>   Dr. Ernst H.K. Stelzer                 Tel: +49 (6221) 387354
>   Scientific Groupleader                 Fax: +49 (6221) 387306
>   Cell Biology and Biophysics Programme
>   EMBL
>   European Molecular Biology Laboratory
>   Meyerhofstrasse 1                      Postfach 10 22 09
>   69117 Heidelberg                       69012 Heidelberg
>
>   e-mail: mailto:stelzer at embl-heidelberg.de
>   http://www.embl.de/ExternalInfo/stelzer/index.html
>   http://www.embl.de/ExternalInfo/stelzer/frames.html?publications
> --------------------------------------------------------------------
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