09/07/06 18:13:01
>>369 (2)
% Prolog
三角形の面積(X1,Y1,X2,Y2,X3,Y3,_三角形の面積) :-
一角を原点へ移動(X1,Y1,X2,Y2,X3,Y3,0,0,X22,Y22,X33,Y33),
_三角形の面積 is abs(X22 * Y33 - Y22 * X33) / 2.
一角を原点へ移動((X1,Y1,X2,Y2,X3,Y3,0,0,X22,Y22,X33,Y33) :-
X22 is X2 - X1,
Y22 is Y2 - Y1,
X33 is X3 - X1,
Y33 is Y3 - X1.