REAL FUNCTION sla_PAV ( 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 sla_BEAR performs an equivalent function except * that the points are specified in the form of spherical * coordinates. * * Called: sla_DPAV * * Patrick Wallace Starlink 23 May 1997 * * Copyright (C) 1997 Rutherford Appleton Laboratory *- IMPLICIT NONE REAL V1(3),V2(3) INTEGER I DOUBLE PRECISION D1(3),D2(3) DOUBLE PRECISION sla_DPAV * Call the double precision version DO I=1,3 D1(I)=V1(I) D2(I)=V2(I) END DO sla_PAV=sla_DPAV(D1,D2) END