As may be apparent from my previous posts, I am in a "If its worth doing, its worth overdoing" sort of competition with a friend of mine. Our goal is arbitrary precision integer arithmetic. I think I am close to getting the data storage working, but now I want to look at the complexity of my multiplication step. I already have it so that if the number is <MIN_MUL_NUM bytes in size then I use "Grade-School multiplication". When my number goes above that, but is still stored in an array (thus <8^sizeof(size_t) bytes) I use Toom-Cook (with k=5 if the other number would like to use Grade-School multiplication, but 3 otherwise). Once I switch over to file stored numbers I intend to implement a Schonhage-Strasse algorithm (I have yet to write it however). However I do have a relatively rapid means by which to determine if my number is far too large (using my header info I can search to see if I have >X files in use for storing the number). As such I would love to implement Furer's algorithm for true asymptotic optimality. However, search as I might I cannot find a description of it anywhere online. Is it just too complicated to use? Or is it protected by some kind of copyright? Where is it?!

It looks like the last one has what I need... This is going to be hard... Thank you!