#! /usr/bin/env python
#
def w_polynomial_value ( n, x ):

#*****************************************************************************80
#
## W_POLYNOMIAL_VALUE: returns the single value W(n,x).
#
#  Discussion:
#
#    In cases where calling W_POLYNOMIAL is inconvenient, because it returns
#    a vector of values for multiple arguments X, this simpler interface
#    may be appropriate.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    12 July 2015
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, integer N, the order of the polynomial.
#
#    Input, real X, the argument of the polynomial.
#
#    Output, real VALUE, the value of W(n,x).
#
  import numpy as np
  from w_polynomial import w_polynomial

  if ( n < 0 ):
    value = 0.0
  else:
    m = 1
    x_vec = np.array ( [ x ] )
    v_vec = w_polynomial ( m, n, x_vec )
    value = v_vec[0,n]

  return value

def w_polynomial_value_test ( ):

#*****************************************************************************80
#
## W_POLYNOMIAL_VALUE_TEST tests W_POLYNOMIAL_VALUE.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    12 July 2015
#
#  Author:
#
#    John Burkardt
#
  import numpy as np
  import platform
  from w_polynomial_values import w_polynomial_values

  print ( '' )
  print ( 'W_POLYNOMIAL_VALUE_TEST:' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  W_POLYNOMIAL_VALUE evaluates the Chebyshev polynomial W(n,x).' )
  print ( '' )
  print ( '                        Tabulated                 Computed' )
  print ( '     N        X           W(n,x)                    W(n,x)                     Error' )
  print ( '' )

  n_data = 0

  while ( True ):

    n_data, n, x, fx1 = w_polynomial_values ( n_data )

    if ( n_data == 0 ):
      break

    fx2 = w_polynomial_value ( n, x )
    e = fx1 - fx2

    print ( '  %4d  %12g  %24.16g  %24.16g  %8.2g' % ( n, x, fx1, fx2, e ) )
# 
#  Terminate.
#
  print ( '' )
  print ( 'W_POLYNOMIAL_VALUE_TEST:' )
  print ( '  Normal end of execution.' )
  return

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