TWOPI ( Twice the value of pi )
DOUBLE PRECISION FUNCTION TWOPI ( )
Return twice the value of pi (the ratio of the circumference of
a circle to its diameter).
The function returns twice the value of pi.
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.D0 ) * 2.D0
The first time the function is referenced, the value is computed
as shown above. The value is saved, and returned directly upon
The code fragment below illustrates the use of TWOPI.
C The longitude of the ascending node is the angle
C between the x-axis and the node vector, n.
NODE = ACOS ( N(1) / VNORM(N) )
IF ( NODE .LT. 0.D0 ) THEN
NODE = NODE + TWOPI()
W.L. Taber (JPL)
I.M. Underwood (JPL)
SPICELIB Version 1.0.2, 28-AUG-1997 (WLT)
Fixed the description in the detailed output section
of the header.
SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)
Comment section for permuted index source lines was added
following the header.
SPICELIB Version 1.0.0, 31-JAN-1990 (WLT) (IMU)