//SINGULAR ExampleA.1.1






LIB "surf.lib";
ring r = 0,(x,y,z),dp;

poly f = -z2+yx2;                      //the Whitney umbrella
map phi = r,x,y,z-1/4x-2;
plot(phi(f));

f =(2*x^2+y^2+z^2-1)^3-(1/10)*x^2*z^3-y^2*z^3;
     // A surprise surface (equation due to Tore Norstrand)
phi = r,1/6z,1/6x,1/6y;               //rescaling
plot(phi(f));