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polynomialmani.pl
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Remove 0*x from answers where terms cancel out

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Hugo Sales 2018-11-25 16:59:03 +00:00
parent 962bab21ba
commit 11f1931a02
1 changed files with 19 additions and 11 deletions
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polymani.pl
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@ -351,7 +351,6 @@ term_to_list(-P, [-P2]) :-
%% Tests:
%% ?- term_to_list(1, X).
%@ X = [1] .
%@ X = [1] .
%% ?- term_to_list(-1, X).
%@ X = [-1] .
%% ?- term_to_list(x, X).
@ -368,7 +367,6 @@ term_to_list(-P, [-P2]) :-
%@ X = -1 .
%% ?- term_to_list(X, [x^1, -1]).
%@ X = -1*x .
%@ X = -1*x .
%% ?- term_to_list(X, [-x^1]).
%@ X = -x .
%% ?- term_to_list(X, [y^1, x^1]).
@ -379,6 +377,8 @@ term_to_list(-P, [-P2]) :-
%@ X = x^4*z^2*y^6 .
%% ?- term_to_list(X, [y^6, z^2, x^4, -2]).
%@ X = -2*x^4*z^2*y^6 .
%% ?- term_to_list(X, [x^1, 0]).
%@ X = 0*x .
%% simplify_term(+Term_In:term, ?Term_Out:term) is det
%
@ -526,7 +526,7 @@ simplify_polynomial(P, P2) :-
%
% Simplifies a polynomial represented as a list.
%
simplify_polynomial_as_list(L, L11) :-
simplify_polynomial_as_list(L, L13) :-
%% Convert each term to a list
maplist(term_to_list, L, L2),
%% Sort each sublist; done so the next
@ -540,23 +540,31 @@ simplify_polynomial_as_list(L, L11) :-
%% Done so the next call simplifies has less work
maplist(sort(0, @=<), L5, L6),
join_similar_terms(L6, L7),
%% Exclude any sublist that includes a 0 (such as the
%% equivalent to the term 0*x)
exclude(member(0), L7, L8),
%% Reverse each sublist, because the next call
%% reverses the result
maplist(reverse, L7, L8),
maplist(term_to_list, L9, L8),
maplist(reverse, L8, L9),
maplist(term_to_list, L10, L9),
%% Delete any 0 from the list
delete(L9, 0, L10),
delete(L10, 0, L11),
%% Sort list converting back gives the result in the correct order
sort(0, @=<, L10, L11).
sort(0, @=<, L11, L12),
(
%% If the list is empty, the result is a list with 0
L12 = [], L13 = [0]
;
%% Otherwise, this is the result
L13 = L12
).
%% Tests:
%% ?- simplify_polynomial_as_list([x, 1, x^2, x*y, 3*x^2, 4*x], L).
%@ L = [1, 4*x^2, 5*x, x*y] .
%@ L = [1, 4*x^2, 5*x, x*y] .
%% ?- simplify_polynomial_as_list([1, x^2, x*y, 3*x^2, -4, -1*x], L).
%@ L = [-3, -1*x, 4*x^2, x*y] .
%@ L = [-3, -1*x, 4*x^2, x*y] .
%% ?- simplify_polynomial_as_list([0*x], L).
%@ L = [0*x] .
%% ?- simplify_polynomial_as_list([0*x, 0], L).
%@ L = [0] .
%% join_similar_terms(+P:ListList, -P2:ListList) is det
%