Is the 3D griddata example correct?

I'm trying to get my head around griddata so that I can plot an intensity as the colour on a 3D surface (a hemisphere). When I start with the example on the Mathworks website "Interpolate 3-D data set over over a grid in the x-y plane" I get the same error as I do in my own code. The code copied from the Mathworks website is as follows:

rng(0,'twister')
x = 2*rand(5000,1)-1; 
y = 2*rand(5000,1)-1; 
z = 2*rand(5000,1)-1;
v = x.^2 + y.^2 + z.^2;

d = -0.8:0.05:0.8;
[xq,yq,zq] = meshgrid(d,d,0);

vq = griddata(x,y,z,v,xq,yq,zq);
surf(xq,yq,vq);
set(gca,'XTick',[-1 -0.5 0 0.5 1]);
set(gca,'YTick',[-1 -0.5 0 0.5 1]);

The subsequent error is as follows:

Error using griddata (line 51)
XI and YI must be the same size or vectors of different orientations.

Error in griddatatest (line 11)
vq = griddata(x,y,z,v,xq,yq,zq);

I presume I have copied and pasted it correctly from Mathworks Central?! I thought it would be a good place to start for my own code...