How to do cubic spline on elements of 3D matrix

Hello,

I have a 2D matrix of size x by y which is a function of a parameter say "spacing". Then a 3D matrix of size x by y by z is formed using the above 2D matrices for z number of spacings.

Let's say spacing = 1:0.5:3 or z = 1:5 for the above 3D matrix. Now, I want to interpolate the 3D matrix for spacings say = 1:0.25:3 or z_new = 1:9 and generate 3D matrix of size x by y by z_new.

Can you please let me know the easiest way to do it. I am interested in using cubic spline method, however, any easier method than spline might also be useful.

Regards,