pas¶

erfa.pas(al, ap, bl, bp)[source]¶

Position-angle from spherical coordinates.

Parameters:

aldouble array
apdouble array
bldouble array
bpdouble array

Returns:

c_retvaldouble array

Notes

Wraps ERFA function eraPas. The ERFA documentation is:

- - - - - - -
 e r a P a s
- - - - - - -

Position-angle from spherical coordinates.

Given:
   al     double     longitude of point A (e.g. RA) in radians
   ap     double     latitude of point A (e.g. Dec) in radians
   bl     double     longitude of point B
   bp     double     latitude of point B

Returned (function value):
          double     position angle of B with respect to A

Notes:

1) The result is the bearing (position angle), in radians, of point
   B with respect to point A.  It is in the range -pi to +pi.  The
   sense is such that if B is a small distance "east" of point A,
   the bearing is approximately +pi/2.

2) Zero is returned if the two points are coincident.

This revision:  2021 May 11

Copyright (C) 2013-2023, NumFOCUS Foundation.
Derived, with permission, from the SOFA library.  See notes at end of file.

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