Re: Bounding Parameters used in FindFit[]
- To: mathgroup at smc.vnet.net
- Subject: [mg75217] Re: Bounding Parameters used in FindFit[]
- From: dh <dh at metrohm.ch>
- Date: Sat, 21 Apr 2007 23:02:33 -0400 (EDT)
- References: <f09fkk$j8$1@smc.vnet.net>
Hi Joshua,
consider the surface of fit-residuals. If this surface has one unique
minimum, you can either give P1 a fixed value or you can use Minimize or
NMinimize to make a constrained fit.
On the other hand, if the surface has several minima, you may force
FindFit to find a minimum that you suits you better by specifying a
start value for e.g. P1 like: {P1,1}.
hope this helps, Daniel
Joshua LaForge wrote:
> Is there a method to limit (bound) the search for a least-squares fit
> with FindFit[] in Mathematica 5.2?
>
> For example I am using FindFit[] to fit a decaying exponential of the
> form P1 * Exp[-t/P2] + P3. I know from the experiment that P3 is
> smaller than the value Mathematica continues to find for that
> parameter. It would be great if there was a way to bound the search
> for P3 to help Mathematica properly optimize P1 and P2.
>
> Joshua LaForge
>
>