rfa 0.5.9

A port ERFA to Rust.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68

use super::{c2ixys::*, s00::*,};
///  Form the celestial to intermediate-frame-of-date matrix for a given
///  date when the CIP X,Y coordinates are known.  IAU 2000.
///
///  Given:
///   * date1,date2 TT as a 2-part Julian Date (Note 1)
///   *  x,y Celestial Intermediate Pole (Note 2)
///
///  Returned:
///   * rc2i celestial-to-intermediate matrix (Note 3)
///
/// # 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 Celestial Intermediate Pole coordinates are the x,y components
///     of the unit vector in the Geocentric Celestial Reference System.
///
///  3) The matrix rc2i is the first stage in the transformation from
///     celestial to terrestrial coordinates:
///
///        [TRS] = RPOM * R_3(ERA) * rc2i * [CRS]
///
///              = RC2T * [CRS]
///
///     where [CRS] is a vector in the Geocentric Celestial Reference
///     System and [TRS] is a vector in the International Terrestrial
///     Reference System (see IERS Conventions 2003), ERA is the Earth
///     Rotation Angle and RPOM is the polar motion matrix.
///
///  4) Although its name does not include "00", This function is in fact
///     specific to the IAU 2000 models.
///
/// # Called:
///    * c2ixys    celestial-to-intermediate matrix, given X,Y and s
///    * s00       the CIO locator s, given X,Y, IAU 2000A
///
/// # Reference:
///   * McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
///     IERS Technical Note No. 32, BKG (2004)
///
///  This revision:  2021 May 11
pub fn c2ixy(date1: f64, date2: f64, x: f64, y: f64,
    rc2i: &mut [[f64; 3]; 3])
{
    /* Compute s and then the matrix. */
       c2ixys(x, y, s00(date1, date2, x, y), rc2i);
    
    /* Finished. */
    
}