#! /usr/bin/env python
#
def ubvec_next ( n, ubvec ):

#*****************************************************************************80
#
## UBVEC_NEXT generates the next UBVEC.
#
#  Discussion:
#
#    The vectors are produced in the order:
#
#    (0,0,...,0),
#    (0,0,...,1),
#    ...
#    (1,1,...,1)
#
#    and the "next" vector after (1,1,...,1) is (0,0,...,0).  That is,
#    we allow wrap around.
#
#    A UBVEC is a vector of N binary digits.
#
#    A UBVEC can be interpreted as a binary representation of an
#    unsigned integer, with the first entry being the coefficient of
#    2^(N-1) and the last entry the coefficient of 1.
#
#    UBVEC   #
#    -----  --
#    00000   0
#    00001   1
#    00010   2
#    10000  16
#
#  Example:
#
#    N = 3
#
#    Input      Output
#    -----      ------
#    0 0 0  =>  0 0 1
#    0 0 1  =>  0 1 0
#    0 1 0  =>  0 1 1
#    0 1 1  =>  1 0 0
#    1 0 0  =>  1 0 1
#    1 0 1  =>  1 1 0
#    1 1 0  =>  1 1 1
#    1 1 1  =>  0 0 0
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, integer N, the dimension of the vectors.
#
#    Input/output, integer UBVEC(N), on output, the successor to the
#    input vector.
#
  for i in range ( n - 1, -1, -1 ):

    if ( ubvec[i] == 0 ):
      ubvec[i] = 1
      return ubvec

    ubvec[i] = 0

  return ubvec

def ubvec_next_test ( ):

#*****************************************************************************80
#
## UBVEC_NEXT_TEST tests UBVEC_NEXT.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
  import numpy as np
  import platform
  from ubvec_print import ubvec_print

  n = 4

  print ( '' )
  print ( 'UBVEC_NEXT_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  UBVEC_NEXT computes the "next" unsigned binary vector.' )
  print ( '' )

  b = np.zeros ( n )

  for i in range ( 0, 17 ):
    ubvec_print ( n, b, '' )
    b = ubvec_next ( n, b )
#
#  Terminate.
#
  print ( '' )
  print ( 'UBVEC_NEXT_TEST' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( )
  ubvec_next_test ( )
  timestamp ( )