d79dd807e6
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1744 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
63 lines
1.5 KiB
Plaintext
63 lines
1.5 KiB
Plaintext
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:- object(primes).
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:- info([
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version is 1.1,
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author is 'Paulo Moura',
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date is 2006/11/26,
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comment is 'Simple example for comparing single and multi-threading calculation of prime numbers.']).
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:- threaded.
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:- public(st_prime_numbers/3).
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:- mode(st_prime_numbers(+integer, +integer, -list), one).
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:- info(st_prime_numbers/3, [
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comment is 'Returns all prime numbers in the given interval using a single calculation thread.',
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argnames is ['Inf', 'Sup', 'Primes']]).
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:- public(mt_prime_numbers/3).
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:- mode(mt_prime_numbers(+integer, +integer, -list), one).
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:- info(mt_prime_numbers/3, [
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comment is 'Returns all prime numbers in the given interval using two calculation threads.',
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argnames is ['Inf', 'Sup', 'Primes']]).
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st_prime_numbers(N, M, Primes) :-
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M > N,
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prime_numbers(N, M, [], Primes).
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mt_prime_numbers(N, M, Primes) :-
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M > N,
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N1 is N + (M - N) // 2,
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N2 is N1 + 1,
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threaded_call(prime_numbers(N, N1, [], Acc)),
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threaded_call(prime_numbers(N2, M, Acc, Primes)),
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threaded_exit(prime_numbers(N, N1, [], Acc)),
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threaded_exit(prime_numbers(N2, M, Acc, Primes)).
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prime_numbers(N, M, Primes, Primes) :-
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N > M,
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!.
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prime_numbers(N, M, Acc, Primes) :-
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( is_prime(N) ->
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Acc2 = [N| Acc]
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; Acc2 = Acc),
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N2 is N + 1,
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prime_numbers(N2, M, Acc2, Primes).
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is_prime(2) :- !.
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is_prime(Prime):-
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Prime > 2,
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Prime mod 2 =:= 1,
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Sqrt is sqrt(Prime),
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is_prime(3, Sqrt, Prime).
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is_prime(N, Sqrt, Prime):-
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( N > Sqrt ->
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true
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; Prime mod N > 0,
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N2 is N + 2,
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is_prime(N2, Sqrt, Prime)
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).
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:- end_object.
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