Singular Manual: makeDivisor

| #### D.5.4.1 makeDivisor 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));

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