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use super::nut80::nut80;
use super::obl80::obl80;
use super::numat::numat;
/// Form the matrix of nutation for a given date, IAU 1980 model.
///
/// Given:
/// * date1,date2 TDB 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.
///
/// # Called:
/// * nut80 nutation, IAU 1980
/// * obl80 mean obliquity, IAU 1980
/// * numat form nutation matrix
///
/// This revision: 2021 May 11
pub fn nutm80(date1: f64, date2: f64, rmatn: &mut [[f64; 3];3])
{
let mut dpsi =0.0; let mut deps =0.0;
/* Nutation components and mean obliquity. */
nut80(date1, date2, &mut dpsi, &mut deps);
let epsa = obl80(date1, date2);
/* Build the rotation matrix. */
numat(epsa, dpsi, deps, rmatn);
/* Finished. */
}