function[u]=grp(g1,g2,N)

g=[g1:(g2-g1)/N:g2]';
[x, y]=meshgrid(g,g);
z=-x.*y.*exp(-x.^2-y.^2);
mesh(x,y,z)
z=reshape(z,1,(N+1)^2);
m=min(z);
M=max(z);
axis([g1 g2 g1 g2 m M])
title('f(x,y)=xye^{-x^2-y^2}')