41 lines
1.0 KiB
Plaintext
41 lines
1.0 KiB
Plaintext
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||
|
|
%%
|
||
|
|
%% 16 June 2003 Bart Demoen, Tom Schrijvers, K.U.Leuven
|
||
|
|
%%
|
||
|
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||
|
|
|
||
|
|
:- module(fibonacci,[fibonacci/0]).
|
||
|
|
:- use_module(library(chr)).
|
||
|
|
|
||
|
|
:- chr_constraint fibonacci/2, cleanup/1.
|
||
|
|
|
||
|
|
%% fibonacci(N,M) is true iff M is the Nth Fibonacci number.
|
||
|
|
|
||
|
|
%% Top-down Evaluation with effective Tabulation
|
||
|
|
%% Contrary to the version in the SICStus manual, this one does "true"
|
||
|
|
%% tabulation
|
||
|
|
|
||
|
|
fibonacci(N,M1) # ID \ fibonacci(N,M2) <=> var(M2) | M1 = M2 pragma passive(ID).
|
||
|
|
|
||
|
|
fibonacci(0,M) ==> M = 1.
|
||
|
|
|
||
|
|
fibonacci(1,M) ==> M = 1.
|
||
|
|
|
||
|
|
fibonacci(N,M) ==>
|
||
|
|
N > 1 |
|
||
|
|
N1 is N-1,
|
||
|
|
fibonacci(N1,M1),
|
||
|
|
N2 is N-2,
|
||
|
|
fibonacci(N2,M2),
|
||
|
|
M is M1 + M2.
|
||
|
|
|
||
|
|
cleanup(L), fibonacci(N,F) <=> L = [N-F|T], cleanup(T).
|
||
|
|
cleanup(L) <=> L = [].
|
||
|
|
|
||
|
|
fibonacci :-
|
||
|
|
fibonacci(15,F),
|
||
|
|
F == 987,
|
||
|
|
cleanup(L),
|
||
|
|
sort(L,SL),
|
||
|
|
SL == [0 - 1,1 - 1,2 - 2,3 - 3,4 - 5,5 - 8,6 - 13,7 - 21,8 - 34,9 - 55,10 - 89,11 - 144,12 - 233,13 - 377,14 - 610,15 - 987].
|