TOMS515
K subsets of an N set

TOMS515, a MATLAB library which lists the subsets of size K selected from a set of size N, by Bill Buckles, Matthew Lybanon.

The text of many ACM TOMS algorithms is available online through ACM: http://calgo.acm.org/ or NETLIB: http://www.netlib.org/toms/index.html.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

TOMS515 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

SUBSET, a MATLAB library which enumerates combinations, partitions, subsets, index sets, and other combinatorial objects.

toms515_test

Author:

Original FORTRAN77 version by Bill Buckles, Matthew Lybanon. MATLAB version by John Burkardt.

Reference:

1. Bill Buckles, Matthew Lybanon,
   Algorithm 515: Generation of a Vector from the Lexicographical Index,
   ACM Transactions on Mathematical Software,
   Volume 3, Number 2, June 1977, pages 180-182.

Source Code:

• binom.m computes the binomial coefficient.
• comb.m selects a subset of order P from a set of order N.
• gamma_log_values.m returns selected values of the logarithm of the gamma function.
• i4_choose.m computes the binomial coefficient.
• i4_choose_check.m reports whether the binomial coefficient can be computed.
• i4_uniform_ab.m returns a scaled pseudorandom I4 between A and B.
• r8_gamma_log.m evaluates the logarithm of the gamma function.
• timestamp.m prints the current YMDHMS date as a time stamp.