Singular

LIB "surfex.lib";
"Example:"; 
// An easy example: a surface with four conical nodes.
ring r = 0, (x,y,z), dp;
poly cayley_cubic = x^3+y^3+z^3+1^3-1/4*(x+y+z+1)^3;
//     plotRotated(cayley_cubic, list(x,y,z));
// A difficult example: a surface with a one-dimensional real component!
poly whitney_umbrella = x^2*z-y^2;
// The Whitney Umbrella without its handle:
plotRotated(whitney_umbrella, list(x,y,z));
// The Whitney Umbrella together with its handle:
plotRotated(whitney_umbrella, list(x,y,z), 2);