% example of 2-D interpolation
% calculate randomly distributed x-y locations
x = rand(100,1)*16 -8;
y = rand(100,1)*16 -8;
% calculate function at x-y locations
r = sqrt(x.^2 + y.^2) + eps;
z = sin(r)./r;
% calculate evenly spaced x and y vectors
xlin = linspace(min(x),max(x),33);
ylin = linspace(min(y),max(y),33);
% calculate grid 
[X,Y] = meshgrid(xlin,ylin);
% interpolate data onto grid points
Z = griddata(x,y,z,X,Y,'cubic');
mesh(X,Y,Z)  % interpolated surface
axis tight; hold on
% display random values (data usded for interpolation)
plot3(x,y,z,'.r','MarkerSize',15) 
hold off