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Diogo Cordeiro 2018-11-18 16:33:09 +00:00
parent 93a43cde52
commit ff8971c141
1 changed files with 187 additions and 112 deletions

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@ -2,61 +2,119 @@
%% Follows 'Coding guidelines for Prolog' - Theory and Practice of Logic Programming
%% https://doi.org/10.1017/S1471068411000391
%% polynomial_variables(-List:atom) is det
%
% List of possible polynomial variables
%
polynomial_variables([x, y, z]).
polynomial_variable_p(X) :-
polynomial_variables(V), member(X, V).
power_p(X) :-
polynomial_variable_p(X), !.
power_p(X^N) :-
polynomial_variable_p(X), integer(N), N > 1, !.
%% polynomial_variable(?X:atom) is det
%
% Returns true if X is a polynomial variable, false otherwise.
%
term_p(N) :-
number(N).
term_p(X) :-
power_p(X).
term_p(L * R) :-
term_p(L),
term_p(R), !.
polynomial_variable(X) :-
polynomial_variables(V),
member(X, V).
polynomial_p(M) :-
term_p(M).
polynomial_p(L + R) :- % Left greedy
polynomial_p(L), % Why?
term_p(R), !.
%% power(+X:atom) is det
%
% Returns true if X is a power monomial, false otherwise.
%
%% ?- polynomial_p(3*x^2+y*z).
%@ true.
%% ?- polynomial_p(x^100*y*z).
%@ true.
%% ?- polynomial_p(x+y+z).
%@ true.
%@ false.
%@ false.
%% ?- polynomial_p(3*x^2+y*z+x^100*y*z).
%@ true.
%@ true.
%% @ false. WIP
simplify_term(1 * P, P) :-
term_p(P), !.
simplify_term(0 * _, 0) :-
power(X) :-
polynomial_variable(X),
!.
power(X^N) :-
polynomial_variable(X),
integer(N),
N > 1,
!.
simplify_term(T, T2) :-
term_to_list(T, L),
sort(0, @=<, L, L2),
join_like_terms(L2, L3),
sort(0, @>=, L3, L4),
term_to_list(T2, L4).
%% ?- simplify_term(2*y*z*x^3*x, X).
%@ X = [z^1, y^1, x^4, 2].
%% term(+N:atom) is det
%
% Returns true if N is a monomial, false otherwise.
%
term(N) :-
number(N).
term(X) :-
power(X).
term(L * R) :-
term(L),
term(R), !.
%% is_term_valid_in_function(+T, +F) is det
%
% Returns true if valid Term, fails with UI message otherwise.
% The fail message reports which Term is invalid and in which
% function the problem ocurred.
%
is_term_valid_in_function(T, F) :-
(
term(T)
;
write("Invalid term in "),
write(F),
write(": "),
write(T),
fail
).
%% polynomial(+M:atom) is det
%
% Returns true if polynomial, false otherwise.
%
polynomial(M) :-
term(M).
polynomial(L + R) :-
polynomial(L),
term(R), !.
%% power_to_canon(+T:atom, -T^N:atom) is det
%
% Returns a canon power term.
%
power_to_canon(T, T^1).
power_to_canon(T^N, T^N).
%% term_to_list(+T, -List) is det
%
%
%
term_to_list(L * N, [N | TS]) :-
number(N),
term_to_list(L, TS),
!.
term_to_list(L * T, [T2 | TS]) :-
power(T),
power_to_canon(T, T2),
term_to_list(L, TS),
!.
term_to_list(T, [T]).
%% ?- term_to_list(2*y*z*23*x*y*x^3*x, X).
%@ X = [x^1, x^3, y^1, x^1, 23, z^1, y^1, 2].
%% ?- term_to_list(X, [2, x^1, y^1]).
%@ X = y^1*x*2.
%@ X = y^1*x*2.
%@ X = y^1*x*2.
%@ X = y*x*2.
%@ X = x*2.
%@ X = 2.
%@ false.
%@ X = [2, x^4, y^1, z^1].
%@ X = [2, x^1, x^3, y^1, z^1].
%% ?- simplify_term(2*y*z*23*x*y*x^3*x, X).
%@ X = [2, 23, x^1, x^3, y^1, z^1].
%@ X = [46, x^4, y^1, z^1].
%@ false.
%@ X = x*2.
%% join_like_terms(List, List)
%
%
%
join_like_terms([T1, T2 | L], [B1^N | L2]) :-
not(number(T1)),
@ -83,81 +141,67 @@ join_like_terms([], []).
%@ T = [6, x^3, y^7].
%@ T = [6, x^3, y].
term_to_list(L * N, [N | TS]) :-
number(N),
term_to_list(L, TS),
!.
term_to_list(L * T, [T2 | TS]) :-
power_p(T),
power_to_canon(T, T2),
term_to_list(L, TS),
!.
term_to_list(T, [T]).
%% simplify_term(+T:atom, -P) is det
%
% Simplifies a term.
%
list_to_term([N | NS], N * L) :-
number(N),
term_to_list(L, NS).
simplify_term(1 * P, P).
simplify_term(0 * _, 0).
simplify_term(T, T2) :-
term_to_list(T, L),
sort(0, @=<, L, L2),
join_like_terms(L2, L3),
sort(0, @>=, L3, L4),
term_to_list(T2, L4).
%% ?- term_to_list(2*y*z*23*x*y*x^3*x, X).
%@ X = [x^1, x^3, y^1, x^1, 23, z^1, y^1, 2].
%% ?- term_to_list(X, [2, x^1, y^1]).
%@ X = y^1*x*2.
%@ X = y^1*x*2.
%@ X = y^1*x*2.
%@ X = y*x*2.
%@ X = x*2.
%@ X = 2.
%% ?- simplify_term(2*y*z*x^3*x, X).
%@ X = [z^1, y^1, x^4, 2].
%@ false.
%@ false.
%@ X = x*2.
%@ X = [2, x^4, y^1, z^1].
%@ X = [2, x^1, x^3, y^1, z^1].
%% ?- simplify_term(2*y*z*23*x*y*x^3*x, X).
%@ X = [2, 23, x^1, x^3, y^1, z^1].
%@ X = [46, x^4, y^1, z^1].
power_to_canon(T, T^1) :-
polynomial_variable_p(T),
!.
power_to_canon(T^N, T^N) :-
polynomial_variable_p(T),
!.
simplify_polynomial(M, M2) :-
term_p(M), simplify_term(M, M2), !.
simplify_polynomial(P + 0, P) :-
term_p(P), !.
simplify_polynomial(0 + P, P) :-
term_p(P), !.
simplify_polynomial(P + M, P2 + M2) :-
simplify_polynomial(P, P2), simplify_term(M, M2).
simplify_polynomial(P + M, P2 + M3) :-
monomial_parts(M, _, XExp),
delete_monomial(P, XExp, M2, P2), !,
add_monomial(M, M2, M3).
simplify_polynomial(P + M, P2 + M2) :-
simplify_polynomial(P, P2), simplify_term(M, M2).
%% ?- simplify_polynomial(1*x+(-1)*x, P).
%% monomial_parts(X, Y, Z)
%
%
%
monomial_parts(X, 1, X) :-
power_p(X), !.
power(X),
!.
monomial_parts(X^N, 1, X^N) :-
power_p(X^N), !.
power(X^N),
!.
monomial_parts(K * M, K, M) :-
coeficient_p(K), !.
number(K),
!.
monomial_parts(K, K, indep) :-
coeficient_p(K), !.
number(K),
!.
delete_monomial(M, X, M, 0) :-
term_p(M),
monomial_parts(M, _, X), !.
monomial_parts(M, _, X),
!.
delete_monomial(M + M2, X, M, M2) :-
term_p(M2), term_p(M),
monomial_parts(M, _, X), !.
term_p(M2),
term_p(M),
monomial_parts(M, _, X),
!.
delete_monomial(P + M, X, M, P) :-
term_p(M), monomial_parts(M, _, X), !.
term_p(M),
monomial_parts(M, _, X),
!.
delete_monomial(P + M2, X, M, P2 + M2) :-
delete_monomial(P, X, M, P2).
add_monomial(K1, K2, K3) :-
number(K1), number(K2), !,
number(K1),
number(K2), !,
K3 is K1 + K2.
add_monomial(M1, M2, M3) :-
monomial_parts(M1, K1, XExp),
@ -173,17 +217,48 @@ p_aux_add_monomial(1, XExp, XExp) :-
!.
p_aux_add_monomial(K, XExp, K * XExp).
%% simplify_polynomial(+P:atom, -P2:atom) is det
%
% Simplifies a polynomial.
%
simplify_polynomial(M, M2) :-
%% Are we dealing with a valid term?
is_term_valid_in_function(M, "simplify_polynomial(M, M2)"),
%% If so, simplify it.
simplify_term(M, M2),
!.
simplify_polynomial(P + 0, P) :-
%% Ensure valid term
is_term_valid_in_function(P, "simplify_polynomial(P + 0, P)"),
!.
simplify_polynomial(0 + P, P) :-
%% Ensure valid term
is_term_valid_in_function(P, "simplify_polynomial(0 + P, P)"),
!.
simplify_polynomial(P + M, P2 + M2) :-
simplify_polynomial(P, P2),
simplify_term(M, M2).
simplify_polynomial(P + M, P2 + M3) :-
monomial_parts(M, _, XExp),
delete_monomial(P, XExp, M2, P2),
!,
add_monomial(M, M2, M3).
simplify_polynomial(P + M, P2 + M2) :-
simplify_polynomial(P, P2),
simplify_term(M, M2).
closure_simplify_polynomial(P, P) :-
simplify_polynomial(P, P2),
P==P2, !.
P==P2,
!.
closure_simplify_polynomial(P, P3) :-
simplify_polynomial(P, P2),
closure_simplify_polynomial(P2, P3), !.
closure_simplify_polynomial(P2, P3),
!.
list_to_term([N | NS], N * L) :-
number(N),
term_to_list(L, NS).
%% ?- simplify_polynomial(1*x+(-1)*x, P).
%@ P = x+ -1*x .
%@ P = x+ -1*x
%@ Unknown action: q (h for help)
%@ Action?
%@ Unknown action: q (h for help)
%@ Action? .