# (Need Help) How to Obtain 2D Interpolation Coefficient?

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Changwoo Lee on 29 Oct 2021
Edited: Changwoo Lee on 29 Oct 2021
I have a pre-setup 2D matrix whose size is [N x N].
Using this data, I want to find the each coefficient k in the below specific funtion.
z=k11*x^2+k22*y^2+...
k12*x*y+...
k1*x+k2*y+k0;
What's the simplest way to obtain these coefficients in Matlab?
It seems that the command 'interp2' does not provide these coefficients.
Matt J on 29 Oct 2021
You have y on both the left and right hand side of the equation. Are they the same y or did you mean
z=k11*x^2+k22*y^2+...
k12*x*y+...
k1*x+k2*y+k0;
Changwoo Lee on 29 Oct 2021
Edited: Changwoo Lee on 29 Oct 2021
The equation in reply is correct. I modified the equation in my question.

Matt J on 29 Oct 2021
Edited: Matt J on 29 Oct 2021
If you have the Curve Fitting Toolbox, you can follow this example
except you would use the 'poly22' model instead of 'poly44'
If you don't have the toolbox, then see one of these FEX submissions.
Changwoo Lee on 29 Oct 2021
Edited: Changwoo Lee on 29 Oct 2021
Thank you very much for your kindness.

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