clear all
z=linspace(-1,1,40);
theta=linspace(0,2*pi,40);
[z,theta]=meshgrid(z,theta);
r=6*sqrt((1-z.^2)./(5.*cos(theta).^2+4));
x=r.*cos(theta);
y=r.*sin(theta);
mesh(x,y,z)
axis equal
grid on
box on
view([130,30])
xlabel('x-axis')
ylabel('y-axis')
zlabel('z-axis')
title('The graph of the ellipsoid x^2/4 + y^2/9 + z^2 =1')