Tim Peters <[EMAIL PROTECTED]> added the comment: Mark, I don't currently have a machine with SVN and a compiler installed, so can't play with patches. I just want to note here that, if you're concerned about speed, it would probably pay to eliminate all library calls except one to frexp(). fmod() in particular is typically way too expensive, taking time proportional to the difference between its inputs' exponents (it emulates "long division" one bit at a time). While float->integer conversion is also "too expensive" on Pentium chips, multiply-and-convert-to-integer is probably a substantially cheaper way to extract bits from the mantissa frexp() delivers; note that this is how the Cookbook lsum() function gets bits, although it gets all 53 bits in one gulp while in C you'd probably want to get, e.g., 30 bits at a time.
Something that's surprised me for decades is how slow platform ldexp() functions are too, given how little they do. Whenever you have a fixed offset E you'd like to add to an exponent, it's almost certainly very much faster to multiply by 2.0**E (when that's a compile-time constant) than to call ldexp(whatever, E). ---------- nosy: +tim_one _______________________________________ Python tracker <[EMAIL PROTECTED]> <http://bugs.python.org/issue2819> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
