#! /usr/bin/env python
#
def ubvec_random ( n, seed ):

#*****************************************************************************80
#
## UBVEC_RANDOM returns a pseudorandom BVEC.
#
#  Discussion:
#
#    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
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
#  Reference:
#
#    Paul Bratley, Bennett Fox, Linus Schrage,
#    A Guide to Simulation,
#    Second Edition,
#    Springer, 1987,
#    ISBN: 0387964673,
#    LC: QA76.9.C65.B73.
#
#    Bennett Fox,
#    Algorithm 647:
#    Implementation and Relative Efficiency of Quasirandom
#    Sequence Generators,
#    ACM Transactions on Mathematical Software,
#    Volume 12, Number 4, December 1986, pages 362-376.
#
#    Pierre L'Ecuyer,
#    Random Number Generation,
#    in Handbook of Simulation,
#    edited by Jerry Banks,
#    Wiley, 1998,
#    ISBN: 0471134031,
#    LC: T57.62.H37.
#
#    Peter Lewis, Allen Goodman, James Miller,
#    A Pseudo-Random Number Generator for the System/360,
#    IBM Systems Journal,
#    Volume 8, Number 2, 1969, pages 136-143.
#
#  Parameters:
#
#    Input, integer N, the order of the vector.
#
#    Input/output, integer SEED, the "seed" value, which should
#    NOT be 0.  On output, SEED has been updated.
#
#    Output, integer UBVEC(N), a pseudorandom binary vector.
#
  import numpy as np
  from sys import exit

  i4_huge      = 2147483647
  i4_huge_half = 1073741823
 
  if ( seed == 0 ):
    print ( '' )
    print ( 'UBVEC_RANDOM - Fatal error!' )
    print ( '  Input value of SEED = 0.' )
    exit ( 'UBVEC_RANDOM - Fatal error!' )

  ubvec = np.zeros ( n )

  for i in range ( 0, n ):

    k = ( seed // 127773 )

    seed = 16807 * ( seed - k * 127773 ) - k * 2836

    if ( seed < 0 ):
      seed = seed + i4_huge

    if ( i4_huge_half < seed ):
      ubvec[i] = 0
    else:
      ubvec[i] = 1

  return ubvec, seed

def ubvec_random_test ( ):

#*****************************************************************************80
#
## UBVEC_RANDOM_TEST tests UBVEC_RANDOM.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
  import platform
  from ubvec_print import ubvec_print

  n = 5

  print ( '' )
  print ( 'UBVEC_RANDOM_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  UBVEC_RANDOM randomizes an unsigned binary vector.' )
  print ( '' )

  seed = 123456789

  for i in range ( 0, 5 ):
    ubvec, seed = ubvec_random ( n, seed )
    ubvec_print ( n, ubvec, '' )
#
#  Terminate.
#
  print ( '' )
  print ( 'UBVEC_RANDOM_TEST' )
  print ( '  Normal end of execution.' )
  return

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