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use crate;
use crate;
use crate;
/// Frame bias and precession matrices, IAU 2000.
///
/// Frame bias and precession, IAU 2000.
///
/// This function is part of the International Astronomical Union's
/// SOFA (Standards of Fundamental Astronomy) software collection.
///
/// Status: canonical model.
///
/// Given:
/// date1,date2 double TT as a 2-part Julian Date (Note 1)
///
/// Returned (function value):
/// (rb, rp, rbp) ([[f64; 3]; 3], [[f64; 3]; 3], [[f64; 3]; 3])
///
/// rb frame bias matrix (Note 2)
/// rp precession matrix (Note 3)
/// rbp bias-precession matrix (Note 4)
///
/// 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 rb transforms vectors from GCRS to mean J2000.0 by
/// applying frame bias.
///
/// 3) The matrix rp transforms vectors from J2000.0 mean equator and
/// equinox to mean equator and equinox of date by applying
/// precession.
///
/// 4) 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.
///
/// Called:
/// iauBi00 frame bias components, IAU 2000
/// iauPr00 IAU 2000 precession adjustments
/// iauIr initialize r-matrix to identity
/// iauRx rotate around X-axis
/// iauRy rotate around Y-axis
/// iauRz rotate around Z-axis
/// iauCr copy r-matrix
/// iauRxr product of two r-matrices
///
/// Reference:
/// "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.
///
/// This revision: 2021 May 11
///
/// SOFA release 2023-10-11
///
/// Copyright (C) 2023 IAU SOFA Board. See notes at end.
///