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MathGroup Archive 2004

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Re: simultaneous fit of multiple data sets

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48096] Re: [mg48024] simultaneous fit of multiple data sets
  • From: Yasvir Tesiram <yat at omrf.ouhsc.edu>
  • Date: Thu, 13 May 2004 00:08:22 -0400 (EDT)
  • References: <200405070829.EAA24821@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,
Your model equation is badly written. There is a closing bracket 
missing at (1 + w^2 * Exp[en.......

Table[{t..  is not closed etc.

It may be worthwhile to break the expression up into smaller parts.

Regards
Yas



On May 7, 2004, at 3:29 AM, Mary Beth Mulcahy wrote:

> I am a chemist using a technique called dielectric spectroscopy, the 
> important
> point is that I get 3 sets of data from a single sample by using 
> different
> frequencies.  The model to fit the data is as follows:
>
> model = Table[{t, .000057 + Sum[(.08/t)*w*Exp[en/(k*t)]/(1 + 
> w^2*Exp[en/(k*t)]
> ^2*1/Cosh[a/(k*t)]^2*Gaussian[en, ampl, x0, sigma], {en, 4, 12, .1}]}, 
> {t, 85,
> 325,5}]
>
> I would like to use Mathematica to simultaneously fit for ampl, xo, 
> sigma, and
> a for the three data sets since the parameters should remain constant 
> over the
> differ frequencies (w).  I am having trouble just getting one 
> frequency to
> fit, but can't decide even if I get that to work, that Mathematica 
> will be
> able to fit three separate curves simultaneously.  I do have the 
> additional
> Experimental Data Analysis (EDA) package.  I can (and have) done this 
> more or
> less by a visual trial and error, but it would be nice to get a 
> chi-squared
> value for my results and to have this be more automated for the future.
>
> Thank you,
>
> Mary Beth Mulcahy
>
>
> University of Colorado


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