NAG Library Routine Document
S13ADF returns the value of the sine integral
via the function name.
|REAL (KIND=nag_wp) S13ADF
S13ADF calculates an approximate value for .
it is based on the Chebyshev expansion
is an implementation-dependent number,
For , to within machine precision.
Abramowitz M and Stegun I A (1972) Handbook of Mathematical Functions (3rd Edition) Dover Publications
- 1: X – REAL (KIND=nag_wp)Input
On entry: the argument of the function.
- 2: IFAIL – INTEGERInput/Output
must be set to
. If you are unfamiliar with this parameter you should refer to Section 3.3
in the Essential Introduction for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value
is recommended. If the output of error messages is undesirable, then the value
is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is
. When the value is used it is essential to test the value of IFAIL on exit.
unless the routine detects an error or a warning has been flagged (see Section 6
6 Error Indicators and Warnings
There are no failure exits from S13ADF. The parameter IFAIL
has been included for consistency with other routines in this chapter.
are the relative errors in the argument and result, respectively, then in principle
The equality may hold if
is greater than the machine precision
due to data errors etc.) but if
is simply due to round-off in the machine representation, then since the factor relating
is always less than one, the accuracy will be limited by machine precision
This example reads values of the argument from a file, evaluates the function at each value of and prints the results.
9.1 Program Text
Program Text (s13adfe.f90)
9.2 Program Data
Program Data (s13adfe.d)
9.3 Program Results
Program Results (s13adfe.r)