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Re: Curve Fitting Problem
From: |
A. Kalten |
Subject: |
Re: Curve Fitting Problem |
Date: |
Thu, 26 Jun 2008 21:06:18 -0400 |
On Thu, 26 Jun 2008 16:47:57 -0700
Scott Carter <address@hidden> wrote:
> AK, in your specific example (which I assume contains a typo and should
> really be (k^2/4)x^2, since as written it's linear)
> I don't see why you aren't just solving the linear regression for y =
> (k/2)x + p
>
> please explain what I'm missing
>
Yes, that was a typo and should be (k^2/4)x^2.
When dealing with data that has error terms any transformation
of the data to get a linear relation is generally not a good idea.
But even transforming the data to get the linear model still
leaves p, which is a known quantity. Functions such as
polyfit will expect both parameters to be unknown and
unconstrained.
I am looking for some off-the-shelf function that will allow
me to specify parts of the model and that will just determine
the unknown parameters. There do not seem to be any off-the-shelf
packages that will do this and probably the only recourse is
to do some custom programming.
AK