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use crate*;
/// Precession-rate part of the IAU 2000 precession-nutation models
/// (part of MHB2000).
///
/// Given:
/// * date1,date2 TT as a 2-part Julian Date (Note 1)
///
/// Returned:
/// * dpsipr,depspr precession corrections (Notes 2,3)
///
/// # 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 precession adjustments are expressed as "nutation
/// components", corrections in longitude and obliquity with respect
/// to the J2000.0 equinox and ecliptic.
///
/// 3) Although the precession adjustments are stated to be with respect
/// to Lieske et al. (1977), the MHB2000 model does not specify which
/// set of Euler angles are to be used and how the adjustments are to
/// be applied. The most literal and straightforward procedure is to
/// adopt the 4-rotation epsilon_0, psi_A, omega_A, xi_A option, and
/// to add dpsipr to psi_A and depspr to both omega_A and eps_A.
///
/// 4) This is an implementation of one aspect of the IAU 2000A nutation
/// model, formally adopted by the IAU General Assembly in 2000,
/// namely MHB2000 (Mathews et al. 2002).
///
/// # References:
/// * Lieske, J.H., Lederle, T., Fricke, W. & Morando, B., "Expressions
/// for the precession quantities based upon the IAU (1976) System of
/// Astronomical Constants", Astron.Astrophys., 58, 1-16 (1977)
/// * Mathews, P.M., Herring, T.A., Buffet, B.A., "Modeling of nutation
/// and precession New nutation series for nonrigid Earth and
/// insights into the Earth's interior", J.Geophys.Res., 107, B4,
/// 2002. The MHB2000 code itself was obtained on 9th September 2002
/// from ftp://maia.usno.navy.mil/conv2000/chapter5/IAU2000A.
/// * Wallace, P.T., "Software for Implementing the IAU 2000
/// Resolutions", in IERS Workshop 5.1 (2002).
///
/// This revision: 2021 May 11