subset
subset,
a FORTRAN90 code which
enumerates, generates, randomizes, ranks and unranks combinatorial objects
including combinations, compositions, Gray codes, index sets, partitions,
permutations, polynomials, subsets, and Young tables. Backtracking
routines are included to solve some combinatorial problems. Other
routines handle continued fractions, Diophantine equations, and
Pythagorean triples.
These include the enumeration, generation, random
selection, ranking and unranking of

COMP, compositions of an integer N into K parts;

COMPNZ, compositions of an integer N into K parts,
with no zero parts;

EQUIV's, partitions of a set of N objects;

I4_PARTITION's, partitions of an integer;

I4POLY's, integer polynomials in factorial, Newton,
power sum, or Taylor form;

I4VEC's, integer vectors;

KSUB's, subsets of size K, from a set of N objects;

MULTIPERM's, permutations of the N objects, some of which
are indistinguishable.

PERM's, permutations of the first N integers;

R8POLY's, real polynomials in factorial, Newton,
power sum, or Taylor form;

KSUB's, subsets of a set of N objects;

vectors whose entries range from 1 to N;

YTB's, Young tables;
Other objects considered include

the Bell numbers,

Catalan numbers,

congruence equations.

continued fractions,

DEC's, decimal numbers represented as a mantissa and a power of 10;

DERANGE's, derangements (permutations that leave no element in place),

DVEC's, decimal numbers represented as a vector of digits;

falling factorials (20*19*18...),

GRAY, Gray codes,

matrix permanents (similar to determinants, but harder to compute,
if you can believe that),

MorseThue numbers,

pentagonal numbers,

primitive Pythagorean triples: relatively prime integers such that a^2 + b^2 = c^2

RAT's, rational numbers represented as a pair of integers;

rising factorials (7*8*9...).
Licensing:
The computer code and data files described and made available on this web page
are distributed under
the MIT license
Languages:
subset is available in
a C version and
a C++ version and
a FORTRAN90 version and
a MATLAB version and
an Octave version and
a Python version.
Related Data and Programs:
BACKTRACK_BINARY_RC,
a FORTRAN90 code which
carries out a backtrack search for a set of binary decisions, using
reverse communication.
CHANGE_MAKING,
a FORTRAN90 code which
considers the change making problem,
in which a given sum is to be formed using coins of various denominations.
COMBINATION_LOCK,
a FORTRAN90 code which
simulates the process of determining the secret combination of a lock.
COMBO,
a FORTRAN90 code which
includes many combinatorial routines.
FLOYD,
a FORTRAN90 code which
implements Floyd's algorithm for finding the shortest distance between pairs of
nodes on a directed graph.
GRAFPACK,
a FORTRAN90 code which
carries out operations on abstract graphs.
KNAPSACK_01,
a FORTRAN90 code which
uses brute force to solve small versions of the 0/1 knapsack problem;
LEGENDRE_PRODUCT_POLYNOMIAL,
a FORTRAN90 code which
defines Legendre product polynomials, creating a multivariate
polynomial as the product of univariate Legendre polynomials.
MONOMIAL,
a FORTRAN90 code which
enumerates, lists, ranks, unranks and randomizes multivariate monomials
in a space of M dimensions, with total degree less than N,
equal to N, or lying within a given range.
PARTIAL_DIGEST,
a FORTRAN90 code which
solves the partial digest problem.
PARTITION_PROBLEM,
a FORTRAN90 code which
seeks solutions of the partition problem, splitting a set of integers into
two subsets with equal sum.
POLYNOMIAL,
a FORTRAN90 code which
adds, multiplies, differentiates, evaluates and prints multivariate
polynomials in a space of M dimensions.
subset_test
SUBSET_SUM,
a FORTRAN90 code which
seeks solutions of the subset sum problem.
TOMS515,
a FORTRAN90 code which
can select subsets of size K from a set of size N.
This is a version of ACM TOMS Algorithm 515,
by Bill Buckles, Matthew Lybanon.
TREEPACK,
a FORTRAN90 code which
carries out computations on trees,
a simple kind of graph that is minimally connected.
UNICYCLE,
a FORTRAN90 code which
considers permutations containing a single cycle, sometimes called
cyclic permutations.
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Source Code:
Last revised on 10 October 2019.