Function Reference
— Function File: zi= bicubic (x, y, z, xi, yi, extrapval)

Return a matrix zi corresponding to the bicubic interpolations at xi and yi of the data supplied as x, y and z. Points outside the grid are set to extrapval

See http://wiki.woodpecker.org.cn/moin/Octave/Bicubic for further information.

See also: interp2

Demonstration 1

The following code

 A=[13,-1,12;5,4,3;1,6,2];
 x=[0,1,4]+10; y=[-10,-9,-8];
 xi=linspace(min(x),max(x),17);
 yi=linspace(min(y),max(y),26)';
 mesh(xi,yi,bicubic(x,y,A,xi,yi));
 [x,y] = meshgrid(x,y);
 hold on; plot3(x(:),y(:),A(:),"b*"); hold off;

Produces the following figure