Function Reference
— Function File: vi = interp3 (x, y,z, v, xi, yi, zi)
— Function File: vi = interp3 (v, xi, yi, zi)
— Function File: vi = interp3 (v, m)
— Function File: vi = interp3 (v)
— Function File: vi = interp3 (..., method)
— Function File: vi = interp3 (..., method, extrapval)

Perform 3-dimensional interpolation. Each element of then 3-dimensional array v represents a value at a location given by the parameters x, y, and z. The parameters x, x, and z are either 3-dimensional arrays of the same size as the array v in the 'meshgrid' format or vectors. The parameters xi, etc respect a similar format to x, etc, and they represent the points at which the array vi is interpolated.

If x, y, z are omitted, they are assumed to be x = 1 : size (v, 2), y = 1 : size (v, 1) and z = 1 : size (v, 3). If m is specified, then the interpolation adds a point half way between each of the interpolation points. This process is performed m times. If only v is specified, then m is assumed to be 1.

Method is one of:

'nearest'
Return the nearest neighbour.
'linear'
Linear interpolation from nearest neighbours.
'cubic'
Cubic interpolation from four nearest neighbours (not implemented yet).
'spline'
Cubic spline interpolation–smooth first and second derivatives throughout the curve.

The default method is 'linear'.

If extrap is the string 'extrap', then extrapolate values beyond the endpoints. If extrap is a number, replace values beyond the endpoints with that number. If extrap is missing, assume NA.