Add points to N-D meshgrid lookup table

I have an enormous 6-dimensional lookup table based on the meshgrid format (with nonuniform grids) that took about 7 days to populate. I have since discovered that for one of the dimensions the range I chose was not quite large enough.

I need the LUT to extend to this larger range but would rather not wait another 1-2 weeks to repopulate an even larger table, since the values I have are fine and don't need to be thrown away.

Is there a way to extend nonuniform meshgrid data to values outside the initial grid limits? If I calculate the lookup values for the range of 6D space I need to extend it to, how do I append this to the original table such that interpn() still works correctly?

Thanks

Answer 1

[Matt J]

In modern Matlab (at least the past 10 years), there is never a need to use meshgrid for interpolation purposes. The inputs can be Grid Vectors.

Vq = interpn(X1,X2,...,Xn,V,Xq1,Xq2,...,Xqn)

This is true for both the interpolated coordinate data X1,..,Xn as well as the query coordinates Xq1,..,Xqn

[Lewis Walker]

Yes but the values V must still be in meshgrid format (N-D matrix) right? The question is about extending V in higher dimensions to new values of, say Xq3

[Matt J]

So you just want to expolate V beyond its current boundaries? If you use griddedInterpolant (instead of interpn), you can choose one of several extrapolation methods

https://www.mathworks.com/help/matlab/ref/griddedinterpolant.html#bvh2cy0-ExtrapolationMethod