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Re: How to use BestFitParameters?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24465] Re: How to use BestFitParameters?
  • From: Lawrence Walker <lwalker701 at earthlink.net>
  • Date: Tue, 18 Jul 2000 00:59:11 -0400 (EDT)
  • Organization: Morgan State University: COMSARE
  • References: <8k0v83$q8s@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Rob,

Use option "RegressionReport -> BestFit" instead.

Lawrence

rob wrote:

> p is a list of data pairs { {x1,y1}, {x2,y2}, ....} and
> when I fit
> this data to a function Mathematica does a pretty good job
> of doing the fit:
>
> NonlinearRegress[p, a/Sqrt[d^2 + (x1 - w0)^2], {x1}, {a,
> d, w0},
>   MaxIterations -> 200, RegressionReport ->
> BestFitParameters]
>
> gives this as an output:
> {BestFitParameters -> {a -> 1.07061, d -> 0.300272, w0 ->
> 28.8068}}
>
> I know it is pretty a pretty good fit to the data because
> I can use
> another program like Excel to plot the curve using these
> parameters
> and display it next to the data.  It sure would be nice to
> do this in
> Mathematica without going to an outside program.  I've
> tried things but I
> can't seem to be able to get to the parameters a, d and
> w0.  I can't
> even list them.  For example,  I'd like to display the
> number
> d/Sqrt[w0^2-d^2]. So I tried this:
>
> d/Sqrt[w0^2-d^2] /. %
>
> All I get is the formula in symbolic form.
>
> Can someone here provide some relief?
>
> Thanks, Rob


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