Singular

D.15.6.7 globalSections

Usage:

globalSections(A); A = divisor.

Assume:

A is a divisor on X.

Return:

a list with a basis of the space of global sections of D.

Theory:

We assume that the qring of X satisfies the S2-condition and that X is smooth. We compute sat((f*J) : I) /f where D = (I)-(J).

LIB "divisors.lib";
ring r=31991,(x,y,z),dp;
ideal I = y^2*z - x*(x-z)*(x+3*z);
qring Q = std(I);
divisor P = makeDivisor(ideal(x,z),ideal(1));
divisor D = multdivisor(4,P);
globalSections(D);