a(A,B) :- B is asin(A).

fit(Points,A,B) :-
	value(A), value(B), fitpoints(Points,A,B).

value(1).
value(2).
value(0.5).
fitpoints([],_,_).
fitpoints([[X,Y]|Points],A,B) :-
	fit(X,Y,A,B), fitpoints(Points,A,B).
fit(X,Y,A,B) :- Y1 is B*sin(A*X), Y-0.01<Y1, Y1<Y+0.01.