#! /usr/bin/env python
#
def i4_uniform_ab ( a, b, seed ):

#*****************************************************************************80
#
## I4_UNIFORM_AB returns a scaled pseudorandom I4.
#
#  Discussion:
#
#    The pseudorandom number will be scaled to be uniformly distributed
#    between A and B.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    05 April 2013
#
#  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 A, B, the minimum and maximum acceptable values.
#
#    Input, integer SEED, a seed for the random number generator.
#
#    Output, integer C, the randomly chosen integer.
#
#    Output, integer SEED, the updated seed.
#
  from sys import exit

  i4_huge = 2147483647

  seed = int ( seed )

  seed = ( seed % i4_huge )

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

  if ( seed == 0 ):
    print ( '' )
    print ( 'I4_UNIFORM_AB - Fatal error!' )
    print ( '  Input SEED = 0!' )
    exit ( 'I4_UNIFORM_AB - Fatal error!' )

  k = ( seed // 127773 )

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

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

  r = seed * 4.656612875E-10
#
#  Scale R to lie between A-0.5 and B+0.5.
#
  a = round ( a )
  b = round ( b )

  r = ( 1.0 - r ) * ( min ( a, b ) - 0.5 ) \
    +         r   * ( max ( a, b ) + 0.5 )
#
#  Use rounding to convert R to an integer between A and B.
#
  value = round ( r )

  value = max ( value, min ( a, b ) )
  value = min ( value, max ( a, b ) )
  value = int ( value )

  return value, seed

def i4_uniform_ab_test ( ):

#*****************************************************************************80
#
## I4_UNIFORM_AB_TEST tests I4_UNIFORM_AB.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    27 October 2014
#
#  Author:
#
#    John Burkardt
#
  import platform

  a = -100
  b = 200
  seed = 123456789

  print ( '' )
  print ( 'I4_UNIFORM_AB_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  I4_UNIFORM_AB computes pseudorandom values' )
  print ( '  in an interval [A,B].' )
  print ( '' )
  print ( '  The lower endpoint A = %d' % ( a ) )
  print ( '  The upper endpoint B = %d' % ( b ) )
  print ( '  The initial seed is %d' % ( seed ) )
  print ( '' )

  for i in range ( 1, 21 ):
    j, seed = i4_uniform_ab ( a, b, seed )
    print ( '  %8d  %8d' % ( i, j ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'I4_UNIFORM_AB_TEST:' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( )
  i4_uniform_ab_test ( )
  timestamp ( )