I'm trying to calculate some simple constants to high precision -- a few tens of millions of decimal places, maybe even a few hundred million. Are there any good programs out there that are fast at doing this? I'm using PARI/GP right now, but it's taking quadratic time to calculate ln(2), which means it would take a year or so to get 100M decimals, which exceeds my patience by about 11-1/2 months. Any thoughts? If I have to program it myself, what's the best way to go about doing that -- in a program like pari, with a package like GMP, or straight-up in C or something similar?