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D.12.4.8 semidiv

Procedure from library hyperel.lib (see hyperel_lib).

Usage:
semidiv(D,h,f);

Return:
list P

Note:
important: Divisor D has to be semireduced!
Computes semireduced divisor P[1][3]*(P[1][1], P[1][2]) +...+ P[size(P)][3]* *(P[size(P)][1], P[size(P)][2]) - (*)infty=div(D[1],D[2])
Curve C:y^2+h(x)y=f(x) is defined over 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;
// Divisor
list D=x2-1,2x-1;
semidiv(D,h,f);
==> [1]:
==>    [1]:
==>       1
==>    [2]:
==>       1
==>    [3]:
==>       1
==> [2]:
==>    [1]:
==>       -1
==>    [2]:
==>       -3
==>    [3]:
==>       1