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yap-6.3/packages/chr/Examples/gcd.chr
2015-10-13 08:17:51 +01:00

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%%
%% 980202, 980311 Thom Fruehwirth, LMU
%% computes greatest common divisor of positive numbers written each as gcd(N)
%%
%% ported to hProlog by Tom Schrijvers
:- module(gcd,[]).
:- use_module( library(chr)).
:- constraints gcd/1.
gcd(0) <=> true.
%%gcd(N) \ gcd(M) <=> N=<M | L is M-N, gcd(L).
gcd(N) \ gcd(M) <=> N=<M | L is M mod N, gcd(L). % faster variant
/*
%% Sample queries
gcd(2),gcd(3).
gcd(1.5),gcd(2.5).
X is 37*11*11*7*3, Y is 11*7*5*3, Z is 37*11*5,gcd(X),gcd(Y),gcd(Z).
*/