Re: Guidance about binary / data files for JTREG tests

[Brian Burkhalter]

For grins here’s an alternative implementation of your algorithm that is slower 
but likely takes less memory:

    private static BitSet primesBS(int n) {
        int nbits = n + 1;
        BitSet bs = new BitSet(nbits);
        bs.set(0, 2, true);
        for (int p = 2; p * p < n;) {
            for (int i = 2 * p; i < nbits; i += p) {
                bs.set(i, true);
            }
            do {
                ++p;
            } while (bs.get(p));
        }
        return bs;
    }

Note that in this case a set bit means NOT prime.

Brian

On Apr 28, 2014, at 11:52 AM, Florian Weimer <fwei...@redhat.com> wrote:

>    private static boolean[] primes(int n) {
>       boolean[] primes = new boolean[n + 1];
>       Arrays.fill(primes, true);
>       primes[0] = false;
>       primes[1] = false;
>       for (int p = 2; p * p < n; ) {
>           for (int i = 2 * p; i < primes.length; i += p)
>               primes[i] = false;
>           do
>               ++p;
>           while (!primes[p]);
>       }
>       return primes;
>    }