Interpolate N-D scattered data

`vq = griddatan(x,v,xq)`

`vq = griddatan(x,v,xq,method)`

`vq = griddatan(x,v,xq,method,options)`

It is not practical to use

`griddatan`

for interpolation in dimensions higher than about 6-D, because the memory required by the underlying triangulation grows exponentially with the number of dimensions.