// For gprolog on omega.uta.edu.
// Include /usr/local/bin in your path.

// These are entered under [user].

gcd2(A,A,A).
gcd2(A,B,G) :- A>B, C is A-B, gcd2(C,B,G).
gcd2(B,A,G) :- A>B, C is A-B, gcd2(C,B,G).

// Queries for either version of prolog.

gcd2(1870,1045,X).

gcd2(210,231,X).

// for http://ioctl.org/logic/prolog-latest
// gtr and leq are in the wrong direction!

gcd2(A, A, A).
gcd2(A, B, G) :- gtr(B,A), sub(A,B,C), gcd2(C, B, G).
gcd2(B, A, G) :- gtr(B,A), sub(A,B,C), gcd2(C, B, G).