# Paste: riced out

Author: | slava |

Mode: | factor |

Date: | Sat, 27 Sep 2008 15:03:59 |

Plain Text |

: <fast-range> ( a b step -- range )
>r over - r>
[ fixnum/i { fixnum } declare ] keep
range boa ; inline
:: nsieve ( n -- pi(n) )
[let | xs [ n [ 1 ] B{ } replicate-as ] |
0 0 xs set-nth-unsafe
0 1 xs set-nth-unsafe
xs [ swap 1 = [| i | i 2 * n 1 - i <fast-range> [ 0 swap xs set-nth-unsafe ] each i ] when drop ] each-index
xs 0 [ + ] reduce ] ;

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