**ACTION:**- Returns the bearing (position angle) of one celestial
direction with respect to another (double precision).
**CALL:**`D = sla_DPAV (V1, V2)`

**GIVEN:**-

*V1***D(3)**direction cosines of one point *V2***D(3)**directions cosines of the other point

**RETURNED:**-

*sla_DPAV***D**position-angle of 2nd point with respect to 1st

**NOTES:**- 1.
- The coordinate frames correspond to ,
*etc.*. - 2.
- The result is the bearing (position angle), in radians, of point V2 as seen from point V1. It is in the range . The sense is such that if V2 is a small distance due east of V1 the result is about . Zero is returned if the two points are coincident.
- 3.
- The routine sla_DBEAR performs an equivalent function except that the points are specified in the form of spherical coordinates.

Starlink User Note 67

P. T. Wallace

12 October 1999

E-mail:ptw@star.rl.ac.uk