40 lines
924 B
Plaintext
40 lines
924 B
Plaintext
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/* Points are going to be the fundamental quantity. */
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/* These will be defined in Cartesian co-ordinates. */
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:- object(point(_X, _Y)).
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:- info([
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authors is 'Paulo Moura',
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version is 1.0,
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date is 2000/4/22,
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comment is 'Parametric object for representing geometric points.',
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parnames is ['X', 'Y'],
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source is 'Example adopted from the POEM system by Ben Staveley-Taylor.']).
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:- public(identical/1).
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:- mode(identical(+nonvar), one).
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:- public(distance/2).
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:- mode(distance(+nonvar, -number), one).
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identical(point(X1, Y1)) :-
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/* succeeds if the argument and owner points are the same. */
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parameter(1, X),
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parameter(2, Y),
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X1 = X,
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Y1 = Y.
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distance(point(X1, Y1), Distance) :-
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/* finds the distance between argument and owner points. */
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parameter(1, X),
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parameter(2, Y),
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Distance is sqrt((X1-X)*(X1-X)+(Y1-Y)*(Y1-Y)).
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:- end_object.
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