Procedure from library divisors.lib (see divisors_lib).
Usage:
makeDivisor(I ,J); I = ideal, J = ideal.
Assume:
I and J are ideals in a qring Q of a smooth irreducible variety X
such that any ideal in Q satisfies the S2 condition.
Return:
a divisor on X
Theory:
The procedure will eliminate all components which are not of codimension 1.
The S2 condition requires that every proper nonzero principal ideal
has pure codimension 1.
Example:
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));