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.help pav Jun99 "Slalib Package"
.nf
REAL FUNCTION slPAV ( V1, V2 )
- - - -
P A V
- - - -
Position angle of one celestial direction with respect to another.
(single precision)
Given:
V1 r(3) direction cosines of one point
V2 r(3) direction cosines of the other point
(The coordinate frames correspond to RA,Dec, Long,Lat etc.)
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.
V1 and V2 do not have to be unit vectors.
The routine slBEAR performs an equivalent function except
that the points are specified in the form of spherical
coordinates.
Called: slDPAV
Patrick Wallace Starlink 23 May 1997
Copyright (C) 1997 Rutherford Appleton Laboratory
Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
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