#! /usr/bin/env python3
#
def normalize ( n, x ):

#****************************************************************************80
#
#  Purpose:
#
#    NORMALIZE scales a vector X so its entries sum to 1.
#
#  Modified:
#
#    19 February 2016
#
#  Author:
#
#    Original C version by Warren Smith.
#    This Python version by John Burkardt.
#
#  Parameters:
#
#    Input, integer N, indicates the size of X.
#
#    Input/output, double X[N+2], the vector to be normalized.
#    Entries X[1] through X[N] will sum to 1 on output.
#

#
#  Sum X.
#
  sum = 0.0
  for i in range ( 1, n + 1 ):
    sum = sum + abs ( x[i] )
#
#  Normalize so that the new sum of X will be 1.
#
  for i in range ( 1, n + 1 ):
    x[i] = x[i] / sum

  return x

def normalize_test ( ):

#*****************************************************************************80
#
## NORMALIZE_TEST tests NORMALIZE.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    19 February 2016
#
#  Author:
#
#    John Burkardt
#
  import platform
  from r8vec_print import r8vec_print
  from r8vec_uniform_01 import r8vec_uniform_01

  print ( '' )
  print ( 'NORMALIZE_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  NORMALIZE normalizes entries 1 through N of a vector' )
  print ( '  of length N+2.' )

  n = 5
  seed = 123456789
  x, seed = r8vec_uniform_01 ( n + 2, seed )
  r8vec_print ( n + 2, x, '  Initial X:' )

  x_norm = 0.0
  for i in range ( 1, n + 1 ):
    x_norm = x_norm + abs ( x[i] )
  print ( '' )
  print ( '  Initial L1 norm of X(1:%d) = %10.6g' % ( n, x_norm ) )

  x = normalize ( n, x )

  r8vec_print ( n + 2, x, '  Normalized X:' )

  x_norm = 0.0
  for i in range ( 1, n + 1 ):
    x_norm = x_norm + abs ( x[i] )
  print ( '' )
  print ( '  Final L1 norm of X(1:%d) = %10.6g' % ( n, x_norm ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'NORMALIZE_TEST' )
  print ( '  Normal end of execution.' )
  return

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