rfa 0.5.9

A port ERFA to Rust.
Documentation 
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use super::pn00b::*;
///  Form the matrix of nutation for a given date, IAU 2000B model.
///
///  Given:
///     * date1,date2  TT as a 2-part Julian Date (Note 1)
///
///  Returned:
///     * rmatn nutation matrix
///
/// # 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 matrix operates in the sense V(true) = rmatn * V(mean), where
///     the p-vector V(true) is with respect to the true equatorial triad
///     of date and the p-vector V(mean) is with respect to the mean
///     equatorial triad of date.
///
///  3) A faster, but slightly less accurate, result (about 1 mas) can be
///     obtained by using instead the eraNum00b function.
///
/// # Called:
///   * pn00b     bias/precession/nutation, IAU 2000B
///
/// # Reference:
///   * Explanatory Supplement to the Astronomical Almanac,
///     P. Kenneth Seidelmann (ed), University Science Books (1992),
///     Section 3.222-3 (p114).
///
///  This revision:  2021 May 11
pub fn num00b(date1: f64, date2: f64, rmatn: &mut [[f64; 3];3])
{
    let mut dpsi =0.0;let mut deps =0.0; let mut epsa =0.0;
    let mut rb = [[0.0;3]; 3]; let mut rp = [[0.0;3]; 3]; let mut rbp=[[0.0;3]; 3]; let mut rbpn=[[0.0;3]; 3];
 
 
 /* Obtain the required matrix (discarding other results). */
    pn00b(date1, date2,
            &mut dpsi, &mut deps, &mut epsa, &mut rb, &mut rp, &mut rbp, rmatn, &mut rbpn);
 
 /* Finished. */
 
 }