On 11-10-06 4:59 AM, Henri Mone wrote:
Dear R users and experts,
I want to fit a shifted parabolic function with the following
functional form to my data:
f(x)=a0*(x+a1)^2+a2
(a0, a1 and a2 are scaling factors.)
What is standard approach to do this in R? I tried the "lm" function
in R but I got problems getting the above functional form.
Any help is welcome :) .
That can be expanded into a regular quadratic:
(a0*a1^2 + a2) + 2*a0*a1*x + a0*x^2
So fit a regular quadratic, and then solve for a0, a1, a2 from the
resulting coefficients. The only tricky bit will be computing errors on
the a's.
Duncan Murdoch
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