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MathGroup Archive 2005

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fitting multiple datasets

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57978] fitting multiple datasets
  • From: Nate Traaseth <traaseth at chem.umn.edu>
  • Date: Wed, 15 Jun 2005 05:58:11 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I have two questions,


1) I have multiple datasets, and one function that depend on multiple 
parameters, of which I would like to find a global best fit to three of the 
parameters. However, within each dataset, I need to specify slightly 
different parameters within the function. For example (not actual function 
and will not make sense),
f(a_,b_,c_,d_,e_) = a*x^5 + b*x^4 + c*x^3 + d*x^2 + e*x
In datasets 1-5, I would like to specify different "a" and "b" values (for 
each dataset), while finding the best single fit (global) for "c," "d," and 
"e" in the function using all datasets.

I see that using "FindFit" one can enter multiple points of the same 
dataset, and minimize the parameters of a function to best fit one dataset, 
but is it possible to enter multiple datasets and find a global minimum for 
multiple parameters in a function? Or do I need to write my own loop in 
Mathematica?


2) When I am doing a minimization using "FindFit" how do I tell the 
minimization routine that I am only interested in solutions (assuming they 
exist as local minima) that satisfy a certain range. For example, a 
solution to a parameter that is only within the range {a,b}.



thanks
Nate



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