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POSieve of Eratosthenes in Erlang
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copied!<p>I'm in the process of learning Erlang. As an exercise I picked up the <a href="http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes" rel="noreferrer">Sieve of Eratosthenes</a> algorithm of generating prime numbers. Here is my code:</p> <pre><code>-module(seed2). -export([get/1]). get(N) -> WorkList = lists:duplicate(N, empty), get(2, N, WorkList, []). get(thats_the_end, _N, _WorkList, ResultList) -> lists:reverse(ResultList); get(CurrentPrime, N, WorkList, ResultList) -> ModWorkList = markAsPrime(CurrentPrime, N, WorkList), NextPrime = findNextPrime(CurrentPrime + 1, N, WorkList), get(NextPrime, N, ModWorkList, [CurrentPrime|ResultList]). markAsPrime(CurrentPrime, N, WorkList) when CurrentPrime =< N -> WorkListMod = replace(CurrentPrime, WorkList, prime), markAllMultiples(CurrentPrime, N, 2*CurrentPrime, WorkListMod). markAllMultiples(_ThePrime, N, TheCurentMark, WorkList) when TheCurentMark > N -> WorkList; markAllMultiples(ThePrime, N, TheCurrentMark, WorkList) -> WorkListMod = replace(TheCurrentMark, WorkList, marked), markAllMultiples(ThePrime, N, TheCurrentMark + ThePrime, WorkListMod). findNextPrime(Iterator, N, _WorkList) when Iterator > N -> thats_the_end; findNextPrime(Iterator, N, WorkList) -> I = lists:nth(Iterator, WorkList), if I =:= empty -> Iterator; true -> findNextPrime(Iterator + 1, N, WorkList) end. replace(N, L, New)-> {L1, [_H|L2]} = lists:split(N - 1, L), lists:append(L1, [New|L2]). </code></pre> <p>This code actually works :) . The problem is that I have this feeling that it is not the best possible implementation. </p> <p>My question is what would be the "erlangish" way of implementing the "Sieve of Eratosthenes"</p> <p>EDIT: OK, Andreas solution is very good but it is slow. Any ideas how to improve that? </p>

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