x=randn(1,20);
y=x'*x;

title('Messy Random Data grid');
mesh(y);
clg

domain = [-3:0.2:3];
range = [-5:0.2:5];
[x,y] = meshgrid(domain,domain);
r = sqrt(x.^2 + y.^2) + 0.00001;
z = sin(pi*r)./(pi*r);
title('sin(pi*r)/(pi*r)');
mesh(r);
clg

title('Sombrero');
mesh(z);
clg

t = range;
s = sinc(t);
s2 = s'*s;
title('Sombrero');
mesh(t,t,s2);
clg

c = cos(t);
c2 = c'*c;
title('cos(x)cos(y) -- mesh');
mesh(t,t,c2);
clg

title('cos(x)cos(y) -- contours');
contour(c2);
clg

sq = t.^2;
sq2 = sq'*sq;
hold on
title('paraboloids');
mesh(t,t,sq2);
mesh(t,t,1-sq2);