Singular

D.6.14.5 discr

Usage:

discr(sem,n); sem ideal, n integer

Assume:

sem is the versal deformation of an ideal of codimension 2.
The first n variables of the ring are treated as variables all the others as parameters.

Return:

ideal describing the discriminant

Note:

This is not a powerful algorithm!

LIB "spcurve.lib";
ring r=32003,(x(1),x(2),x(3)),ds;
ideal curve=x(1)*x(2),x(1)*x(3),x(2)*x(3);
matrix M=isCMcod2(curve);
list l=matrixT1(M,3);
def rneu=semiCMcod2(l[1],std(l[2]));
setring rneu;
discr(semi,3);
==> _[1]=A(1)*A(2)*A(3)