Interp2 is a tool that allows you to interpolate on a gridded domain. So a grid based on meshgrid, in the (x,y) plane. The presumption is you have some array V, that defines V(x,y).
Xq and Yq are now a list of points to interpolate over that grid.
Interp2 is NOT there to interpolate over scattered data points, thus a point cloud in the (x,y) plane. That purpose is served by tools like griddata and scatteredInterpolant.
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