| #### D.12.3.12 cantormult Procedure from library `hyperel.lib` (see hyperel_lib). Usage: cantormult(m,D,h,f); Return: list res=m*D Note: important: Divisor D has to be semireduced! Uses repeated doublings for a faster computation of the reduced divisor m*D. Attention: Factor m=int, this means bounded. For m<0 the inverse of m*D is returned. The divisors are defined over the basering. Curve C: y^2+h(x)y=f(x) is defined over the basering. Example:
    LIB "hyperel.lib";
    ring R=7,x,dp;
    // hyperelliptic curve y^2 + h*y = f
    poly h=x;
    poly f=x5+5x4+6x2+x+3;
    // reduced divisor
    list D=x2-1,2x-1;
    cantormult(34,D,h,f);
    ==> [1]:
    ==>    x2-3x-3
    ==> [2]:
    ==>    x+1

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