#! /usr/bin/env python
#
def c8_cos ( c ):

#*****************************************************************************80
#
## C8_COS evaluates the cosine of a C8.
#
#  Discussion:
#
#    Here we use the relationship:
#
#      C8_COS ( C ) = ( C8_EXP ( i * C ) + C8_EXP ( - i * C ) ) / 2
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    11 February 2015
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, complex C, the argument.
#
#    Output, complex VALUE, the function value.
#
  from c8_exp import c8_exp

  value = ( c8_exp ( 1j * c ) + c8_exp ( - 1j * c ) ) / 2.0

  return value

def c8_cos_test ( ):

#*****************************************************************************80
#
## C8_COS_TEST tests C8_COS.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    11 February 2015
#
#  Author:
#
#    John Burkardt
#
  import numpy as np
  import platform
  from c8_acos import c8_acos
  from c8_uniform_01 import c8_uniform_01

  print ( '' )
  print ( 'C8_COS_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  C8_COS computes the cosine of a C8.' )
  print ( '' )
  print ( '       C1=C8_UNIFORM_01          C2=C8_COS(C1)             C3=C8_ACOS(C2)' )
  print ( '     ---------------------     ---------------------     ---------------------' )
  print ( '' )

  seed = 123456789

  for i in range ( 0, 10 ):
    c1, seed = c8_uniform_01 ( seed )
    c2 = c8_cos ( c1 )
    c3 = c8_acos ( c2 );
    print ( '  (%12f,%12f)  (%12f,%12f)  (%12f,%12f)' \
      % ( c1.real, c1.imag, c2.real, c2.imag, c3.real, c3.imag ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'C8_COS_TEST:' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( )
  c8_cos_test ( )
  timestamp ( )