On 2/22/07, Ruben Zilibowitz
I see that there has been some discussion on the list about prime finding algorithms recently. I just wanted to contribute my own humble algorithm: [snip] Comparing it to some of the algorithms in: http://www.haskell.org/pipermail/haskell-cafe/2007-February/022765.html
It seems to perform reasonably well. It also has the advantage of being quite short.
It has the advantage of conciseness, and for small enough examples will give reasonable results, though computing O(n/log(n)) gcds can be very expensive. One suggestion I would make is to build the list in reverse order. Since the test proceeds through the list from left to right, and an arbitrary positive integer is more likely to be divisible by a small primes than a larger one, this ought to produce a faster result when the input is composite. Steve