- Abstract
Return twice the value of pi (the ratio of the circumference of
a circle to its diameter).
- Required_Reading
None.
- Brief_I/O
The function returns twice the value of pi.
- Detailed_Input
None.
- Detailed_Output
The function returns twice the value of pi (the ratio of
a circle's circumference to its diameter), determined by
the ACOS function. That is,
twopi = acos ( -1. ) * 2.
- Parameters
None.
- Particulars
The first time the function is referenced, the value is computed
as shown above. The value is saved, and returned directly upon
subsequent reference.
- Examples
The code fragment below illustrates the use of twopi_c.
/.
The longitude of the ascending node is the angle
between the x-axis and the node vector, n.
-
./
node = acos ( n[0] / vnorm_c( n ) );
if ( node < 0.D0 )
{
node = node + twopi_c();
}
- Restrictions
None.
- Exceptions
Error free.
- Files
None.
- Author_and_Institution
W.L. Taber (JPL)
I.M. Underwood (JPL)
E.D. Wright (JPL)
- Literature_References
None.
- Version
-CSPICE Version 1.0.0, 08-FEB-1998 (EDW)
- Index_Entries
twice the value of pi
- Link to routine source