ecpp_disc_cost, ecpp_disc_cost_v, ecpp_disc_cost_n

The estimated cost of realising a step with the discriminant d, in units of one scalar multiplication on the curve at a few thousand bits: the twists, the numerical computation of the class polynomials of the class field tower (cheap with Weber's function, which is usable for even $D$ and, through the order of conductor 2, for odd $D$ when the $v$ of $4n = t^2 + |D| v^2$ is even, as veven says), and the descent through the prime factors $p$ of $h$ (a square root for $p = 2$, radicals or a small powering for $p = 3$, a $p$-th root or a powering of a degree $p$ polynomial otherwise), or the cost of a root of the genus field factor if that is smaller. ecpp_disc_cost_n uses $n$ modulo 5, 7, 11 and 13 (nmodp, or the average over $n$ if NULL) and scales the cost of the class polynomial numerics, which does not depend on $n$, to the bit size of $n$. ecpp_disc_cost is the optimistic estimate (with veven = 1) used to order and admit the pool. Class numbers with a prime factor above 13 get a cost above ECPP_DISC_COST_MAX.