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# eqeq94

erfa.eqeq94(date1, date2)

  Equation of the equinoxes, IAU 1994 model.

  Parameters:
    date1 double array
    date2 double array
  Returns:
    c_retval double array

  Notes

  Wraps ERFA function `eraEqeq94`. The ERFA documentation is:

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       e r a E q e q 9 4
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      Equation of the equinoxes, IAU 1994 model.

      Given:
         date1,date2   double     TDB date (Note 1)

      Returned (function value):
                       double     equation of the equinoxes (Note 2)

      Notes:

      1) The date date1+date2 is a Julian Date, apportioned in any
         convenient way between the two arguments.  For example,
         JD(TT)=2450123.7 could be expressed in any of these ways,
         among others:

                date1          date2

             2450123.7           0.0       (JD method)
             2451545.0       -1421.3       (J2000 method)
             2400000.5       50123.2       (MJD method)
             2450123.5           0.2       (date & time method)

         The JD method is the most natural and convenient to use in
         cases where the loss of several decimal digits of resolution
         is acceptable.  The J2000 method is best matched to the way
         the argument is handled internally and will deliver the
         optimum resolution.  The MJD method and the date & time methods
         are both good compromises between resolution and convenience.

      2) The result, which is in radians, operates in the following sense:

            Greenwich apparent ST = GMST + equation of the equinoxes

      Called:
         eraAnpm      normalize angle into range +/- pi
         eraNut80     nutation, IAU 1980
         eraObl80     mean obliquity, IAU 1980

      References:

         IAU Resolution C7, Recommendation 3 (1994).

         Capitaine, N. & Gontier, A.-M., 1993, Astron.Astrophys., 275,
         645-650.

      This revision:  2021 May 11

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