Description:
Bearing (position angle) of one point in a sphere relative to another.
Invocation
pa =
palDbear( double a1, double b1, double a2, double b2 );
Arguments
a1 = double
(Given)
Longitude of point 1 (e.g. RA) in radians.
b1 = double (Given)
Latitude of
point 1 (e.g. Dec) in radians.
a2 = double (Given)
Longitude of point 2 in radians.
b2 =
double (Given)
Latitude of point 2 in radians.
Returned Value
The result is the bearing
(position angle), in radians, of point
A2,B2 as seen from point A1,B1. It is in the range
/- pi. If
A2,B2 is due east
of A1,B1 the bearing is pi/2.
Zero is returned
if the two points are coincident.
Notes:
Copyright © 2012 Science and Technology Facilities Council.
Copyright © 2014 Cornell University.
Copyright © 2015 Tim Jenness