rfa 0.5.9

A port ERFA to Rust.
Documentation 
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use super::{gmst06::*, gst06a::*};
use crate::vector_matrix::angle_ops::anpm::*;
///  Equation of the equinoxes, compatible with IAU 2000 resolutions and
///  IAU 2006/2000A precession-nutation.
///
///  Given:
///   * date1,date2  TT as a 2-part Julian Date (Note 1)
///
///  Returned (function value):
///   * equation of the equinoxes (Note 2)
///
/// # Notes:
///
///  1) The TT 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:
///   * anpm      normalize angle into range +/- pi
///   * gst06a    Greenwich apparent sidereal time, IAU 2006/2000A
///   * gmst06    Greenwich mean sidereal time, IAU 2006
///
/// # Reference:
///   * McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003),
///     IERS Technical Note No. 32, BKG
///
///  This revision:  2021 May 11

pub fn ee06a(date1: f64, date2: f64)->f64
{

 /* Apparent and mean sidereal times. */
    let gst06a = gst06a(0.0, 0.0, date1, date2);
    let gmst06 = gmst06(0.0, 0.0, date1, date2);
 
 /* Equation of the equinoxes. */
    anpm(gst06a - gmst06)
  
 /* Finished. */
 
 }