Quote:
Originally Posted by Prime95
Have you played with improving PRAC?
I recently did and gained one or two percent.

The gain is not quite as large for me for the smaller inputs I am dealing with, but it is a gain of about 1%.
It also seemed to help very slightly for me to define the cost functions to include the faster nature of a square versus a multiply. Doing that increases the total dups / adds ratio very slightly in stage 1.
In my tinyecm code (< 64 bits) where there are just a few fixed and very small B1 values, I found that in a few cases the cost of PRAC(p1*p2) is cheaper than PRAC(p1) + PRAC(p2). It isn't practical to test combinations of primes like this in real time for arbitrary (and larger) B1. But I wonder if it is worth compiling a list of prime pairs that are cheaper when combined below bounds like 1M, 3M, 11M, etc.