Position angle of one celestial direction with respect to another.

pa = palDpav( double v1[3], double v2[3] );

v1 = double [3] (Given)

v2 = double [3] (Given)

The result is the bearing (position angle), in radians, of point

V2 with respect to point V1. It is in the range $+$/- pi. The

sense is such that if V2 is a small distance east of V1, the

bearing is about $+$pi/2. Zero is returned if the two points

are coincident.

• The coordinate frames correspond to RA,Dec, Long,Lat etc.

• Uses eraPap(). See SOFA/ERFA documentation for details.