ANN: Pyrex - a language for writing Python extension modules

[David Eppstein]

In article <mailman.1017952983.647.clpa-moderators at python.org>,
 Greg Ewing <greg at cosc.canterbury.ac.nz> wrote:

> Oh, yeah, here's the example. It finds prime
> numbers at C speed.
> 
> def primes(int kmax):
>   cdef int n, k, i
>   cdef int p[1000]
>   result = []
>   if kmax > 1000:
>     kmax = 1000
>   k = 0
>   n = 2
>   while k < kmax:
>     i = 0
>     while i < k and n % p[i] <> 0:
>       i = i + 1
>     if i == k:
>       p[k] = n
>       k = k + 1
>       result.append(n)
>     n = n + 1
>   return result

Not to criticise your project, but this is not a good example to use -- 
you've started with a very unnecessarily slow algorithm.  For finding 
prime numbers, the Sieve of Eratosthenes is much better.  See e.g.
<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/117119> which I 
implemented using simple generators so you don't need the kmax parameter.

-- 
David Eppstein       UC Irvine Dept. of Information & Computer Science
eppstein at ics.uci.edu http://www.ics.uci.edu/~eppstein/