#include "sofam.h"
void iauBp00(double date1, double date2,
double rb[3][3], double rp[3][3], double rbp[3][3])
/*
** - - - - - - - -
** i a u B p 0 0
** - - - - - - - -
**
** 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:
** rb double[3][3] frame bias matrix (Note 2)
** rp double[3][3] precession matrix (Note 3)
** rbp double[3][3] 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.
**
** 5) It is permissible to re-use the same array in the returned
** arguments. The arrays are filled in the order given.
**
** 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: 2010 January 18
**
** SOFA release 2012-03-01
**
** Copyright (C) 2012 IAU SOFA Board. See notes at end.
*/
{
/* J2000.0 obliquity (Lieske et al. 1977) */
const double EPS0 = 84381.448 * DAS2R;
double t, dpsibi, depsbi;
double dra0, psia77, oma77, chia, dpsipr, depspr, psia, oma,
rbw[3][3];
/* Interval between fundamental epoch J2000.0 and current date (JC). */
t = ((date1 - DJ00) + date2) / DJC;
/* Frame bias. */
iauBi00(&dpsibi, &depsbi, &dra0);
/* Precession angles (Lieske et al. 1977) */
psia77 = (5038.7784 + (-1.07259 + (-0.001147) * t) * t) * t * DAS2R;
oma77 = EPS0 + ((0.05127 + (-0.007726) * t) * t) * t * DAS2R;
chia = ( 10.5526 + (-2.38064 + (-0.001125) * t) * t) * t * DAS2R;
/* Apply IAU 2000 precession corrections. */
iauPr00(date1, date2, &dpsipr, &depspr);
psia = psia77 + dpsipr;
oma = oma77 + depspr;
/* Frame bias matrix: GCRS to J2000.0. */
iauIr(rbw);
iauRz(dra0, rbw);
iauRy(dpsibi * sin(EPS0), rbw);
iauRx(-depsbi, rbw);
iauCr(rbw, rb);
/* Precession matrix: J2000.0 to mean of date. */
iauIr(rp);
iauRx(EPS0, rp);
iauRz(-psia, rp);
iauRx(-oma, rp);
iauRz(chia, rp);
/* Bias-precession matrix: GCRS to mean of date. */
iauRxr(rp, rbw, rbp);
return;
/*----------------------------------------------------------------------
**
** Copyright (C) 2012
** Standards Of Fundamental Astronomy Board
** of the International Astronomical Union.
**
** =====================
** SOFA Software License
** =====================
**
** NOTICE TO USER:
**
** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
** CONDITIONS WHICH APPLY TO ITS USE.
**
** 1. The Software is owned by the IAU SOFA Board ("SOFA").
**
** 2. Permission is granted to anyone to use the SOFA software for any
** purpose, including commercial applications, free of charge and
** without payment of royalties, subject to the conditions and
** restrictions listed below.
**
** 3. You (the user) may copy and distribute SOFA source code to others,
** and use and adapt its code and algorithms in your own software,
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**
** a) Your work shall be marked or carry a statement that it
** (i) uses routines and computations derived by you from
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**
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**
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**
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**
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**
** Note that, as originally distributed, the SOFA software is
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**
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**
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*
** In any published work or commercial product which uses the SOFA
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**
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**
**--------------------------------------------------------------------*/
}