x=linspace(0,4,100);
y=linspace(0,4,100);
[X,Y]=meshgrid(x,y);
Z=X.^2+Y.^2;
Z1=2*(X.^2+Y.^2);
Z3=linspace(-1,50,100);
Z2=Z3';
for i=1:99
    Z2=[Z2,Z3'];
end
size(Z)
Y1=X.^2;
mesh(X,Y,Z);
hold on
mesh(X,Y,Z1);
hold on
mesh(X,X,Z2)
hold on
mesh(X,Y1,Z2)