TOMS515
K subsets of an N set

TOMS515 is a FORTRAN90 library which lists the subsets of size K selected from a set of size N, by Bill Buckles, Matthew Lybanon.

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 FORTRAN90 library which enumerates combinations, partitions, subsets, index sets, and other combinatorial objects.

Author:

Original FORTRAN77 version by Bill Buckles, Matthew Lybanon. FORTRAN90 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:

• toms515.f90, the source code.

Examples and Tests:

• toms515_test.f90, a sample calling program.
• toms515_test.txt, the output from a run of the sample program.

List of Routines:

• BINOM computes the binomial coefficient.
• COMB selects a subset of order P from a set of order N.
• I4_CHOOSE_CHECK reports whether the binomial coefficient can be computed.
• I4_UNIFORM_AB returns a scaled pseudorandom I4 between A and B.
• R8_GAMMA_LOG evaluates the logarithm of the gamma function.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.