simultaneous fit of multiple data sets

*To*: mathgroup at smc.vnet.net*Subject*: [mg48024] simultaneous fit of multiple data sets*From*: Mary Beth Mulcahy <Mary.Mulcahy at colorado.edu>*Date*: Fri, 7 May 2004 04:29:42 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

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

**Follow-Ups**:**Re: simultaneous fit of multiple data sets***From:*Yasvir Tesiram <yat@omrf.ouhsc.edu>