#! /usr/bin/env python # def si_values ( n_data ): #*****************************************************************************80 # ## SI_VALUES returns some values of the sine integral function. # # Discussion: # # SI(X) = integral ( 0 <= T <= X ) sin ( T ) / T dt # # In Mathematica, the function can be evaluated by: # # SinIntegral[x] # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 21 February 2015 # # Author: # # John Burkardt # # Reference: # # Milton Abramowitz and Irene Stegun, # Handbook of Mathematical Functions, # US Department of Commerce, 1964. # # Stephen Wolfram, # The Mathematica Book, # Fourth Edition, # Wolfram Media / Cambridge University Press, 1999. # # Parameters: # # Input/output, integer N_DATA. The user sets N_DATA to 0 before the # first call. On each call, the routine increments N_DATA by 1, and # returns the corresponding data; when there is no more data, the # output value of N_DATA will be 0 again. # # Output, real X, the argument of the function. # # Output, real F, the value of the function. # import numpy as np n_max = 16 f_vec = np.array ( ( \ 0.4931074180430667E+00, \ 0.5881288096080801E+00, \ 0.6812222391166113E+00, \ 0.7720957854819966E+00, \ 0.8604707107452929E+00, \ 0.9460830703671830E+00, \ 0.1108047199013719E+01, \ 0.1256226732779218E+01, \ 0.1389180485870438E+01, \ 0.1505816780255579E+01, \ 0.1605412976802695E+01, \ 0.1778520173443827E+01, \ 0.1848652527999468E+01, \ 0.1833125398665997E+01, \ 0.1758203138949053E+01, \ 0.1654140414379244E+01 )) x_vec = np.array ( ( \ 0.5E+00, \ 0.6E+00, \ 0.7E+00, \ 0.8E+00, \ 0.9E+00, \ 1.0E+00, \ 1.2E+00, \ 1.4E+00, \ 1.6E+00, \ 1.8E+00, \ 2.0E+00, \ 2.5E+00, \ 3.0E+00, \ 3.5E+00, \ 4.0E+00, \ 4.5E+00 )) if ( n_data < 0 ): n_data = 0 if ( n_max <= n_data ): n_data = 0 x = 0.0 f = 0.0 else: x = x_vec[n_data] f = f_vec[n_data] n_data = n_data + 1 return n_data, x, f def si_values_test ( ): #*****************************************************************************80 # ## SI_VALUES_TEST demonstrates the use of SI_VALUES. # # Licensing: # # This code is distributed under the GNU LGPL license. # # Modified: # # 19 January 2015 # # Author: # # John Burkardt # import platform print ( '' ) print ( 'SI_VALUES_TEST:' ) print ( ' Python version: %s' % ( platform.python_version ( ) ) ) print ( ' SI_VALUES stores values of the SI function.' ) print ( '' ) print ( ' X SI(X)' ) print ( '' ) n_data = 0 while ( True ): n_data, x, f = si_values ( n_data ) if ( n_data == 0 ): break print ( ' %12f %24.16f' % ( x, f ) ) # # Terminate. # print ( '' ) print ( 'SI_VALUES_TEST:' ) print ( ' Normal end of execution.' ) return if ( __name__ == '__main__' ): from timestamp import timestamp timestamp ( ) si_values_test ( ) timestamp ( )