Consider the following example:
[x,y,z] = peaks;
surf(x,y,z)
hold on
[~,i] = max(z(:));
h = scatter3(x(i),y(i),z(i),'filled');
h.SizeData = 150;
[~,i] = min(z(:));
h = scatter3(x(i),y(i),z(i),'filled');
h.SizeData = 150;
hold off
Does that make sense?
The 2nd arg of the min/max commands tells you the index of the element that is the min or max. You can use that index to get the X, Y, and Z coordinate for the surface.
