# How to do quadratic interpolation in two dimensions on a plane

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Kayson Christensen on 19 May 2022
Commented: Matt J on 27 May 2022
I'm working on a project which analyzes the air velocity in front of a fan. We took measurments at various positions on an x-y plane placed perpendicular to the air flow, and read velocity in the z-direction only. I tried to create a surface plot to help visually show what the flow is like, but since I only have a few data points it looked really jagged. I then tried to use the interp2 function to try and smooth out the points but it came out like this:
I realize the interp2 is a linear interpolation technique, but is there a way we could do a quadratic fit in two dimensions? Since this should look more like a bell curve, as you would expect. All of this data is recorded in matricies, with identical x and y matricies for the plane, and a U matrix for the velocities. I appreciate any help I can get!
Kayson Christensen on 27 May 2022
The planes are set parallel with the flow from the fans (as if you're looking down on the full setup). In that photo, the U velocity direction was shown. There are two more charts like in that photo recording the data for V and W at the same plane. It's a complicated setup, but I found it was the easiest way of recording accurate data.

Matt J on 24 May 2022
I realize the interp2 is a linear interpolation technique
No, you have several alternatives to linear interpolation with interp2,
Maybe try with 'cubic'?
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Matt J on 27 May 2022
You're quite welcome but please Accept-click the answer to indicate that it worked.

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