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.


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.


Original FORTRAN77 version by Bill Buckles, Matthew Lybanon. FORTRAN90 version by John Burkardt.


  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:

Examples and Tests:

List of Routines:

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

Last revised on 28 March 2016.