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Re: Mathematica question

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  • Subject: [mg8134] Re: [mg8111] Mathematica question
  • From: seanross at
  • Date: Fri, 15 Aug 1997 23:41:46 -0400
  • Sender: owner-wri-mathgroup at

> Hello,
>   I am a beginner Mathematica user and am having a bit of trouble with a
> curve fit.  I'm sorry to bother you, but when I try to get into the
> archives our computer doesn't seem to like it.
>   I am trying to fit a fluorescence lifetime decay that is at least a
> double exponential.  I am really confused when following the curve fit
> section of the manuel and have tried a few things but with no success.  I
> would appreciate if you could give me a few hints or insight to curve
> fitting.
>   Thank you for your time,
>   Julia Meinershagen

It is hard to know how to respond since your question is a little vague.
The built-in function "Fit" is really only designed to fit things to
algebraic series.  They do give an example in the Mathematica book about
taking the Log of the function, then fitting and taking the exponential,
but this is a rather tortuous way to fit functions.  I recommend looking
in the NonlinearFit add-on package.  This function allows you to choose
an arbitrary basis set of functions.  If you are using Mma 3.0, look it
up in the Add-on Packages section of the on-line help.  If you are using
2.2, I recommend buying a copy of the 2.2 guide to standard add-on
packages.  In either case, <<Statistics`NonlinearFit` will load the
package for you.

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