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Re: Re: Fit with constraints?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23322] Re: [mg23316] Re: Fit with constraints?
  • From: David Withoff <withoff at wolfram.com>
  • Date: Tue, 2 May 2000 00:43:05 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Martin Rommel <Martin_Rommel at mac.com> wrote in message
news:8eg5ee$giq at smc.vnet.net...
> It seems the Fit function lacks the option to fix a point (like "set
> intercept" in Excel).
>
> How is that best done?
>
> Martin

Fixing a point or setting an intercept just means using a model
that always passes through a particular point, as in

In[1]:= Fit[{{1,2},{3,7},{4,6},{7,9},{11,14}}, x-4, x]

Out[1]= 1.64706 (-4 + x)

which fits the data to a straight line that passes through 4 (that is,
it sets the y intercept to 4). If you have an example where you're
not sure how to do this, you could try posting your example, or
contacting technical support. In any case, fixing a point is just
a simple modification of the model in the input to Fit.

Dave Withoff
Wolfram Research


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