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Merge pull request #2 from diogogithub/scale_polynomial

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Scale polynomial
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Diogo Cordeiro 2018-11-22 12:53:07 +00:00 committed by GitHub
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1 changed files with 90 additions and 52 deletions
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polimani.pl
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@ -1,4 +1,5 @@
%% -*- mode: prolog-*-
%% vim: set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
%% Follows 'Coding guidelines for Prolog' - Theory and Practice of Logic Programming
%% https://doi.org/10.1017/S1471068411000391
@ -9,7 +10,7 @@
%% reversing of a predicate.
:- use_module(library(clpfd)).
%% polynomial_variable_list(-List:atom) is det
%% polynomial_variable_list(-List) is det
%
% List of possible polynomial variables
%
@ -22,30 +23,23 @@ polynomial_variable_list([x, y, z]).
polynomial_variable(X) :-
polynomial_variable_list(V),
member(X, V).
%% polynomial_variable(P) :-
%% polynomial_variable_list(V),
%% member(X, V),
%% P = X^N,
%% N == 1.
%% Tests:
%% ?- polynomial_variable(x).
%@ true .
%% ?- polynomial_variable(x^(1)).
%% ?- polynomial_variable(a).
%@ false.
%% power(+X:atom) is semidet
%
% Returns true if X is a power term, false otherwise.
% Fully reversible.
%
power(P^N) :-
%% CPL(FD) library predicate to perform integer comparassions in a reversible way
%% If 0 > N succeds, fail, otherwise check if X is a valid variable
(zcompare((<), 0, N), polynomial_variable(P)); fail.
%% if(zcompare((>), 0, N),
%% fail,
%% polynomial_variable(X)
%% ).
(
zcompare((<), 0, N),
polynomial_variable(P)
;
fail
).
power(X) :-
polynomial_variable(X).
%% Tests:
@ -54,42 +48,14 @@ power(X) :-
%% ?- power(x^1).
%@ true .
%% ?- power(x^3).
%@ false.
%@ false.
%@ false.
%@ true .
%@ true .
%% ?- power(x^(-3)).
%@ false.
%@ false.
%@ true .
%@ false.
%@ true .
%@ false.
%@ error.
%% ?- power(X).
%@ X = x ;
%@ X = y ;
%@ X = z.
%% if(+P, -T, -F) is det
%
% A simple implementation of an if predicate.
% Returns T if P is true
% or F if P otherwise
%
%% if(If_1, Then_0, Else_0) :-
%% call(If_1, T),
%% ( T == true -> call(Then_0)
%% ; T == false -> call(Else_0)
%% ; nonvar(T) -> throw(error(type_error(boolean,T),_))
%% ; /* var(T) */ throw(error(instantiation_error,_))
%% ).
if(P, T, F) :- (P == true, T); F.
%% ?- if(true, N = 1, N = 2).
%@ N = 1 .
%% ?- if(false, N = 1, N = 2).
%@ N = 2.
%% term(+N:atom) is det
%
% Returns true if N is a term, false otherwise.
@ -116,17 +82,17 @@ term(L * R) :-
% predicate the problem ocurred.
%
is_term_valid_in_predicate(T, F) :-
(
(
term(T)
;
;
write("Invalid term in "),
write(F),
write(": "),
write(T),
fail
).
).
%% Tests:
%% ?- is_term_valid_in_predicate(1, "Foo").
%% ?- is_term_valid_in_predicate(1, "Chuck Norris").
%@ true .
%% polynomial(+M:atom) is det
@ -259,20 +225,24 @@ join_like_terms([], []).
%% simplify_polynomial(+P:atom, -P2:atom) is det
%
% Simplifies a polynomial.
% TODO: not everything is a +, there are -
%
simplify_polynomial(M, M2) :-
%% Are we dealing with a valid term?
is_term_valid_in_predicate(M, "simplify_polynomial(M, M2)"),
%is_term_valid_in_predicate(M, "simplify_polynomial(M, M2)"),
term(M),
%% If so, simplify it.
simplify_term(M, M2),
!.
simplify_polynomial(P + 0, P) :-
%% Ensure valid term
is_term_valid_in_predicate(P, "simplify_polynomial(P + 0, P)"),
%is_term_valid_in_predicate(P, "simplify_polynomial(P + 0, P)"),
term(P),
!.
simplify_polynomial(0 + P, P) :-
%% Ensure valid term
is_term_valid_in_predicate(P, "simplify_polynomial(0 + P, P)"),
%is_term_valid_in_predicate(P, "simplify_polynomial(0 + P, P)"),
term(P),
!.
simplify_polynomial(P + M, P2 + M2) :-
simplify_polynomial(P, P2),
@ -295,7 +265,6 @@ simplify_polynomial(P + M, P2 + M2) :-
%
% Simplifies a list of polynomials
%
simplify_polynomial_list([L1], L3) :-
simplify_polynomial(L1, L2),
L3 = [L2].
@ -306,6 +275,75 @@ simplify_polynomial_list([L1|L2],L3) :-
% There is nothing further to compute at this point
!.
%% polynomial_to_list(+P:polynomial, -L:List)
%
% Converts a polynomial in a list.
% TODO: not everything is a +, there are -
%
polynomial_to_list(T1 + T2, L) :-
polynomial_to_list(T1, L1),
L = [T2|L1],
% The others computations are semantically meaningless
!.
polynomial_to_list(P, L) :-
L = [P].
%% Tests:
%%?- polynomial_to_list(2*x^2+5+y*2, S).
%@S = [y*2, 5, 2*x^2].
%% list_to_polynomial(+P:polynomial, -L:List)
%
% Converts a list in a polynomial.
% TODO: not everything is a +, there are -
%
list_to_polynomial([T1|T2], P) :-
list_to_polynomial(T2, L1),
(
not(L1 = []),
P = L1+T1
;
P = T1
),
% The others computations are semantically meaningless
!.
list_to_polynomial(T, P) :-
P = T.
%% Tests:
%% TODO
%% append_two_atoms_with_star(+V1, +V2, -R) is det
%
% Returns R = V1 * V2
%
append_two_atoms_with_star(V1, V2, R) :-
% Convert term V2 into a string V3
term_string(V2, V3),
% Concat atom V1 with * into a compound V4
atom_concat(V1, *, V4),
% Concat atom V4 with V3 into a compound S
atom_concat(V4, V3, S),
% Convert compound S into a term R
term_string(R, S).
%% Tests:
% ?- append_two_atoms_with_star(2, x^2, R).
%@ R = 2*x^2.
%@ R = 2*x^2.
%@ R = 2*3.
%% scale_polynomial(+P:polynomial,+C:constant,-S:polynomial) is det
%
% Scales a polynomial with a constant
%
scale_polynomial(P, C, S) :-
polynomial_to_list(P, L),
maplist(append_two_atoms_with_star(C), L, L2),
list_to_polynomial(L2, S).
%simplify_polynomial(S1, S).
%% Tests:
%% ?- scale_polynomial(3*x^2, 2, S).
%@ S = 2*3*x^2.
%@ S = 2*(3*x^2).
%% monomial_parts(X, Y, Z)
%
% TODO Maybe remove