Test Collatz

Jan Burse, created Sep 01. 2016
/**
* Balanced execution of the collatz function.
* Jekejeke Prolog version.
*
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*/
:- use_module(library(runtime/distributed)).
:- use_module(library(advanced/arith)).
/*****************************************************************/
/* Normal Test Cases */
/*****************************************************************/
between(10000, 20000, X),
collatz(X, _).
balance(X^( between(10000, 20000, X),
collatz(X, _)), 2).
balance(X^( between(10000, 20000, X),
collatz(X, _)), 4).
balance(X^( between(10000, 20000, X),
collatz(X, _)), 8).
once(( between(10000, 20000, X),
collatz(X, _),
X = 16666)).
once(balance(X^( between(10000, 20000, X),
collatz(X, _),
X = 16666), 2)).
once(balance(X^( between(10000, 20000, X),
collatz(X, _),
X = 16666), 4)).
once(balance(X^( between(10000, 20000, X),
collatz(X, _),
X = 16666), 8)).
/*****************************************************************/
/* Reduced Test Cases */
/*****************************************************************/
between(1000, 2000, X),
collatz(X, _).
balance(X^( between(1000, 2000, X),
collatz(X, _)), 2).
balance(X^( between(1000, 2000, X),
collatz(X, _)), 4).
balance(X^( between(1000, 2000, X),
collatz(X, _)), 8).
once(( between(1000, 2000, X),
collatz(X, _),
X = 1666)).
once(balance(X^( between(1000, 2000, X),
collatz(X, _),
X = 1666), 2)).
once(balance(X^( between(1000, 2000, X),
collatz(X, _),
X = 1666), 4)).
once(balance(X^( between(1000, 2000, X),
collatz(X, _),
X = 1666), 8)).
/*****************************************************************/
/* The Collatz Function */
/*****************************************************************/
collatz(1, 0) :- !.
collatz(I, N) :-
1 =:= I/\1, !,
I0 is I*3+1,
collatz(I0, N0),
N is N0+1.
collatz(I, N) :-
I0 is I>>1,
collatz(I0, N0),
N is N0+1.

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