We present novel explicit formulas for arithmetic in the divisor class group of a
curve.
Our formulas handle all cases of inputs and outputs without having to fall back on a
generic method. We also improve on the most commonly occurring case by reducing
the number of required field inversions to one at the cost of a small number
of additional field operations, resulting in running times that are between
11 and 21% faster than the prior state of the art depending on the field
size, and even more for small field sizes when nontypical cases frequently
arise.
Keywords
computational number theory, computational algebraic
geometry, divisor arithmetic, C34 curves, genus 3
nonhyperelliptic curves