%  =================================================================
%  ==                                                             ==
%  ==          An Introduction to ARTIFICIAL INTELLIGENCE         ==
%  ==                  Janet Finlay and Alan Dix                  ==
%  ==                       UCL Press, 1996                       ==
%  ==                                                             ==
%  =================================================================
%  ==                                                             ==
%  ==                   mathematical utilities                    ==
%  ==                                                             ==
%  ==            Prolog example, Alan Dix, August 1996            ==
%  ==                                                             ==
%  =================================================================


%  max/3, min/3, fdiv/3, round/2

min(N,M,N) :- N =< M.
min(N,M,M) :- N > M.
max(N,M,N) :- N >= M.
max(N,M,M) :- N < M.


%  some Prologs don't handle floating point division.
%  choose the definition which works best on your implementation

% fdiv(Num,Den,Res) :- Res is Num/Den.

fdiv(Num,Den,Res) :- Res is ((Num*1000000.0)/Den)*0.000001.


%  the definition of round/2 relies on / always giving integer result
%  this is likely to be very dependent on the way your Prolog works,
%  so you may need to redefine this.


round(X,N) :-  N is (X+0.499)/1.