20 lines
541 B
Prolog
20 lines
541 B
Prolog
pi_spigot :-
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pi(X),
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forall(member(Y, X), write(Y)).
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pi(OUT) :-
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pi(1, 180, 60, 2, OUT).
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pi(Q, R, T, I, OUT) :-
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freeze(OUT,
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( OUT = [Digit | OUT_]
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-> U is 3 * (3 * I + 1) * (3 * I + 2),
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Y is (Q * (27 * I - 12) + 5 * R) // (5 * T),
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Digit is Y,
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Q2 is 10 * Q * I * (2 * I - 1),
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R2 is 10 * U * (Q * (5 * I - 2) + R - Y * T),
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T2 is T * U,
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I2 is I + 1,
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pi(Q2, R2, T2, I2, OUT_)
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; true)).
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