Data commit

Task/Pi/Prolog/pi.pro

@@ -0,0 +1,19 @@
+pi_spigot :-
+    pi(X),
+    forall(member(Y, X), write(Y)).
+
+pi(OUT) :-
+    pi(1, 180, 60, 2, OUT).
+
+pi(Q, R, T, I, OUT) :-
+    freeze(OUT,
+           (   OUT = [Digit | OUT_]
+           ->  U is 3 * (3 * I + 1) * (3 * I + 2),
+               Y is (Q * (27 * I - 12) + 5 * R) // (5 * T),
+               Digit is Y,
+               Q2 is 10 * Q * I * (2 * I - 1),
+               R2 is 10 * U * (Q * (5 * I - 2) + R - Y * T),
+               T2 is T * U,
+               I2 is I + 1,
+               pi(Q2, R2, T2, I2, OUT_)
+           ;   true)).