%% Quiver
% By Ned Gulley, 6-21-93.
%
% Superimpose QUIVER on top of a PCOLOR plot with interpolated shading. The
% function shown is the PEAKS function.
    
% Copyright 1984-2004 The MathWorks, Inc.
% $Revision: 5.9.4.1 $  $Date: 2004/03/02 21:47:03 $

x = -3:.2:3;
y = -3:.2:3;
[xx,yy] = meshgrid(x,y);
zz = peaks(xx,yy);
hold on
pcolor(x,y,zz);
axis([-3 3 -3 3]);
colormap((jet+white)/2);
shading interp
[px,py] = gradient(zz,.2,.2);
quiver(x,y,px,py,2,'k');
axis off
hold off