Second partial derivatine on scattered grid

I have data on non uniform grid (scattered data). And I need to calculate second partial derivative d^f/dxdy. And it is not clear for me how to approximate this derivative in right way with less error. Could you help me with that? Is there some good way to approximate the second derivative without interpolating data and making uniform grid?

Answer 1

[Star Strider]

All the built-in MATLAB functions, such as del2 (link) assume a constant grid or sampling interval.

The File Exchange has several contributions on the Laplacian (link) that might allow for non-constant grid intervals. I did not look closely at them.