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use ;
/// Precession-nutation, IAU 2000B model: a multi-purpose function,
/// supporting classical (equinox-based) use directly and CIO-based
/// use indirectly.
///
/// Given:
/// * date1,date2 TT as a 2-part Julian Date (Note 1)
///
/// Returned:
/// * dpsi,deps nutation (Note 2)
/// * epsa mean obliquity (Note 3)
/// * rb frame bias matrix (Note 4)
/// * rp precession matrix (Note 5)
/// * rbp bias-precession matrix (Note 6)
/// * rn nutation matrix (Note 7)
/// * rbpn GCRS-to-true matrix (Notes 8,9)
///
/// # 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 nutation components (luni-solar + planetary, IAU 2000B) in
/// longitude and obliquity are in radians and with respect to the
/// equinox and ecliptic of date. For more accurate results, but
/// at the cost of increased computation, use the eraPn00a function.
/// For the utmost accuracy, use the eraPn00 function, where the
/// nutation components are caller-specified.
///
/// 3) The mean obliquity is consistent with the IAU 2000 precession.
///
/// 4) The matrix rb transforms vectors from GCRS to J2000.0 mean
/// equator and equinox by applying frame bias.
///
/// 5) The matrix rp transforms vectors from J2000.0 mean equator and
/// equinox to mean equator and equinox of date by applying
/// precession.
///
/// 6) The matrix rbp transforms vectors from GCRS to mean equator and
/// equinox of date by applying frame bias then precession. It is
/// the product rp x rb.
///
/// 7) The matrix rn transforms vectors from mean equator and equinox
/// of date to true equator and equinox of date by applying the
/// nutation (luni-solar + planetary).
///
/// 8) The matrix rbpn transforms vectors from GCRS to true equator and
/// equinox of date. It is the product rn x rbp, applying frame
/// bias, precession and nutation in that order.
///
/// 9) The X,Y,Z coordinates of the IAU 2000B Celestial Intermediate
/// Pole are elements (3,1-3) of the GCRS-to-true matrix,
/// i.e. rbpn[2][0-2].
///
/// 10) It is permissible to re-use the same array in the returned
/// arguments. The arrays are filled in the stated order.
///
/// Called:
/// * nut00b nutation, IAU 2000B
/// * pn00 bias/precession/nutation results, IAU 2000
///
/// # Reference:
/// * Capitaine, N., Chapront, J., Lambert, S. and Wallace, P.,
/// "Expressions for the Celestial Intermediate Pole and Celestial
/// Ephemeris Origin consistent with the IAU 2000A precession-
/// nutation model", Astron.Astrophys. 400, 1145-1154 (2003).
/// n.b. The celestial ephemeris origin (CEO) was renamed "celestial
/// intermediate origin" (CIO) by IAU 2006 Resolution 2.