links

< home >
< unix stuff >
< code >
< writing >
< archive >
< music >
< photos >
< recipes >
< site map >
< about badcomputer >

The sieve of eratosthenes

forth

\ Sieve of Eratosthenes in Forth
\ Written by Rob Hoelz
\ To run: Load this file into a Forth interpreter, and call <limit> MAIN

VARIABLE LIMIT

: RANGE RECURSIVE 2DUP =
    IF DROP
    ELSE DUP -ROT 1- RANGE
    THEN ;

: REMOVE RECURSIVE DUP DEPTH 3 - >
    IF DROP
    ELSE DUP 1+ PICK 2 PICK MOD 0=
        IF DUP 1+ ROLL DROP REMOVE
        ELSE 1+ REMOVE
        THEN
    THEN ;

: REMOVE.MULTIPLES 1 REMOVE ;

: GENERATE RECURSIVE DUP . DUP DUP * LIMIT @ >
    IF DROP
    ELSE REMOVE.MULTIPLES DROP GENERATE
    THEN ;

: PRINT.PRIMES RECURSIVE DEPTH 0>
    IF . PRINT.PRIMES
    ELSE CR
    THEN ;

: MAIN
LIMIT !
2 LIMIT @ RANGE GENERATE PRINT.PRIMES ;

back to Eratosthenes page

stats

It is Monday September 08, 2008 12:52 am
This page served 761 times
This page last modified: April 14, 2008 11:28 am
Your IP address is: 38.103.63.61
You are browsing using: CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
You are browsing from: United States.
badcomputer.org's uptime: 00:52:31 up 39 days, 15:59, 2 users, load average: 0.01, 0.02, 0.00