#! /usr/bin/env python
#
def ubvec_add ( n, ubvec1, ubvec2 ):

#*****************************************************************************80
#
## UBVEC_ADD adds two unsigned binary vectors.
#
#  Discussion:
#
#    A UBVEC is an integer vector of binary digits, intended to
#    represent a nonnegative integer.  UBVEC(1) is the units digit, UBVEC(N)
#    is the coefficient of 2^(N-1).
#
#  Example:
#
#    N = 4
#
#     UBVEC1       +  UBVEC2       =  UBVEC3
#
#    ( 1 0 0 0 )   + ( 1 1 0 0 )   = ( 0 0 1 0 )
#
#      1           +   3           =   4
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, integer N, the length of the vectors.
#
#    Input, integer UBVEC1(N), UBVEC2(N), the vectors to be added.
#
#    Output, integer UBVEC3(N), the sum of the two input vectors.
#
  import numpy as np

  overflow = False

  ubvec3 = np.zeros ( n )
#
#  Add.
#
  for i in range ( 0, n ):
    ubvec3[i] = ubvec1[i] + ubvec2[i]
#
#  Carry.
#
  for i in range ( n - 1, -1, -1 ):
    while ( 2 <= ubvec3[i] ):
      ubvec3[i] = ubvec3[i] - 2
      if ( 0 < i ):
        ubvec3[i-1] = ubvec3[i-1] + 1
      else:
        overflow = True

  return ubvec3

def ubvec_add_test ( ):

#*****************************************************************************80
#
## UBVEC_ADD_TEST tests UBVEC_ADD
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    22 November 2015
#
#  Author:
#
#    John Burkardt
#
  import platform
  from i4_uniform_ab import i4_uniform_ab
  from ui4_to_ubvec import ui4_to_ubvec
  from ubvec_to_ui4 import ubvec_to_ui4

  n = 10
  seed = 123456789

  print ( '' )
  print ( 'UBVEC_ADD_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  UBVEC_ADD adds unsigned binary vectors representing' )
  print ( '  unsigned integers' )
  print ( '' )
  print ( '        I        J        K = I + J' )
  print ( '' )

  for test in range ( 0, 10 ):
    
    i, seed = i4_uniform_ab ( 0, 100, seed )
    j, seed = i4_uniform_ab ( 0, 100, seed )

    print ( '' )

    print ( '  %8d  %8d' % ( i, j ) )

    k = i + j

    print ( '  Directly:           %8d' % ( k ) )

    ubvec1 = ui4_to_ubvec ( i, n )
    ubvec2 = ui4_to_ubvec ( j, n )

    ubvec3 = ubvec_add ( n, ubvec1, ubvec2 )
    k = ubvec_to_ui4 ( n, ubvec3 )

    print ( '  UBVEC_ADD           %8d' % ( k ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'UBVEC_ADD_TEST' )
  print ( '  Normal end of execution.' )
  return

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