View Single Post
Old 2008-03-23, 12:46   #5
akruppa's Avatar
Aug 2002

2,467 Posts

Sieve the special-q on the side that has the larger norms. If your SNFS polynomial is well-suited to the number you're factoring (degree 5 for difficulty ~170, degree 6 for difficulty ~240), the norms on both sides will be very close in size and you can sieve either side (or even both). With lopsided polynomials such as degree 6 for relatively small numbers, or degree 4 for relatively large ones, choosing the special-q on the "right" side has considerable impact on yield. For GNFS, the algebraic side is usually the larger one.

akruppa is offline   Reply With Quote