hamming.pl : Solves Hamming Problem Solves the Hamming Problem which is to build the infinite ascending sequence of positive numbers containing no prime factors other than 2, 3 and 5 (cf. http://en.wikipedia.org/wiki/Hamming_problem).
How to use: The constraint hamming/0 displays the unlimited sequence of Hamming numbers. As the sequence is unlimited the program does not terminate!
Program: Change the code, then submit! /* hamming.pl: Solves Hamming Problem (C) Thom.Fruehwirth at uni-ulm.de, 1997/02/24 This program is distributed under the terms of the GNU General Public License: http://www.gnu.org/licenses/gpl.html %% DESCRIPTION Solves the Hamming Problem which is to build the infinite ascending sequence of positive numbers containing no prime factors other than 2, 3 and 5 (cf. http://en.wikipedia.org/wiki/Hamming_problem). %% HOW TO USE The constraint *hamming/0* displays the unlimited sequence of Hamming numbers.# As the sequence is unlimited the program does not terminate! %% SAMPLE QUERIES Q: hamming. A: not terminating! %% 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 25, 27, 30, ... */ :- module(hamming, [hamming/0]). :- use_module(library(chr)). %% Deprecated syntax used for SICStus 3.x %handler hamming. %constraints hamming/0,watch/1,multlist/3,merge/3. %% Syntax for SWI / SICStus 4.x :- chr_constraint hamming/0,watch/1,multlist/3,merge/3. %% hamming %% the list of Hamming numbers is constructed and printed in parallel hamming <=> watch(L), L=[1|L235], multlist(L,2,L2), multlist(L,3,L3), multlist(L,5,L5), merge(L2,L3,L23), merge(L5,L23,L235). %% watch(L) %% print elements of list L recursively watch([X|L]) <=> print(X),nl, watch(L). %% multlist(L,N,LN) %% multiply each element of list L with N, resulting in list LN %% here only do multiplication for 1st element, then use multlist recursively multlist([X|L],N,XLN) <=> XN is X*N, XLN=[XN|LN], multlist(L,N,LN). %% merge(In1,In2,Out) %% merge sorted lists In1 and In2 into sorted list Out recursively merge([X|In1],[Y|In2],XYOut) <=> X=:=Y | XYOut=[X|Out], merge(In1,In2,Out). merge([X|In1],[Y|In2],XYOut) <=> X<Y | XYOut=[X|Out], merge(In1,[Y|In2],Out). merge([X|In1],[Y|In2],XYOut) <=> X>Y | XYOut=[Y|Out], merge([X|In1],In2,Out).
Console: Enter query or select example from below, then submit and wait for answer! % loading functions/hamming.pl | ?- consult(...). yes [0.854 seconds] | ?-