筛法生成质数（素数）的生成器，质数素数,Python语言: 筛法

筛法生成质数（素数）的生成器，质数素数,Python语言: 筛法

Python语言: 筛法生成质数（素数）的生成器#!/usr/bin/python# -*- coding: utf-8 -*- import mathdef gen_sieve(ceiling=None):    if ceiling is not None:        if ceiling % 2 == 0:            ceiling -= 1        highest_prime = math.ceil(math.sqrt(ceiling))    last_val = 1    found_primes = []    yield 2    while ceiling is None or ceiling > last_val:        current_val = None        while current_val is None:            current_val = last_val = last_val + 2            for prime, square in found_primes:                if current_val < square:                     break                if current_val % prime == 0:                    current_val = None                    break        yield current_val        if ceiling is None or highest_prime > last_val:            found_primes.append((current_val, current_val ** 2))def isprime(n):    for fac in gen_sieve(int(math.ceil(math.sqrt(n)))):        if n % fac == 0 and n != fac:            return fac    return 0#该片段来自于http://byrx.net