//SINGULAR ExampleA.9.10


LIB "deform.lib";
ring r         = 0,(x,y,z,u,v),ds;
matrix m[2][4] = x,y,z,u,y,z,u,v;
ideal f        = minor(m,2);     //ideal of 2x2 minors of m
versal(f);        //computes the semi-universal deformation 
setring Px;       //the data are contained in the ring Px

Fs;
Js;

ring s = 0,x,ds;
poly f = x4;
versal(f);
setring Px;
Fs;                          //the semi-universal deformation

ideal sing = Fs,diff(Fs,x);  //the singular locus
eliminate(sing,x);           //the discriminant

LIB"surf.lib";
plot(256C3-27B4+144AB2C-128A2C2-4A3B2+16A4C);