I am happy to announce the first public release of pyprimes, a pure- Python module for generating prime numbers, primality tests, and prime factorisation.
http://pypi.python.org/pypi/pyprimes/0.1.1a With pyprimes, you can compare a number of algorithms for generating and testing primes. It includes fast algorithms for lazily generating primes on demand, such as the Croft Spiral, as well as terrible examples of algorithms to avoid, such as Turner's Sieve (sometimes known as "the Sleight on Eratosthenes"). Examples: py> import pyprimes py> pyprimes.isprime(3300454933) True py> pyprimes.factors(3300454934) [2, 7, 14969, 15749L] py> for p in pyprimes.primes(): ... if p < 500000: continue ... if p > 500100: break ... print p ... 500009 500029 500041 500057 500069 500083 A note on performance: Generating large prime numbers (hundreds of digits) is extremely computationally intensive. A pure-Python solution like pyprimes is unlikely to be suitable for such large numbers, and I make no claim that it will break any world-records. But many popular and common prime number generators can't even deal well with *five* digit primes, slowing down to a crawl. pyprimes is in some cases hundreds of times faster than such prime generators. pyprimes includes examples of these algorithms so you can compare them for yourself: py> from time import time py> def test(generator): ... t = time() ... for p in generator(): ... if p > 10000: break ... return time() - t ... py> test(pyprimes.primes) 0.013000965118408203 py> test(pyprimes.naive_primes1) 4.1489889621734619 -- Steven -- http://mail.python.org/mailman/listinfo/python-list
