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+#include "erfa.h"
+
+void eraApci(double date1, double date2,
+ double ebpv[2][3], double ehp[3],
+ double x, double y, double s,
+ eraASTROM *astrom)
+/*
+** - - - - - - - -
+** e r a A p c i
+** - - - - - - - -
+**
+** For a terrestrial observer, prepare star-independent astrometry
+** parameters for transformations between ICRS and geocentric CIRS
+** coordinates. The Earth ephemeris and CIP/CIO are supplied by the
+** caller.
+**
+** The parameters produced by this function are required in the
+** parallax, light deflection, aberration, and bias-precession-nutation
+** parts of the astrometric transformation chain.
+**
+** Given:
+** date1 double TDB as a 2-part...
+** date2 double ...Julian Date (Note 1)
+** ebpv double[2][3] Earth barycentric position/velocity (au, au/day)
+** ehp double[3] Earth heliocentric position (au)
+** x,y double CIP X,Y (components of unit vector)
+** s double the CIO locator s (radians)
+**
+** Returned:
+** astrom eraASTROM* star-independent astrometry parameters:
+** pmt double PM time interval (SSB, Julian years)
+** eb double[3] SSB to observer (vector, au)
+** eh double[3] Sun to observer (unit vector)
+** em double distance from Sun to observer (au)
+** v double[3] barycentric observer velocity (vector, c)
+** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
+** bpn double[3][3] bias-precession-nutation matrix
+** along double unchanged
+** xpl double unchanged
+** ypl double unchanged
+** sphi double unchanged
+** cphi double unchanged
+** diurab double unchanged
+** eral double unchanged
+** refa double unchanged
+** refb double unchanged
+**
+** Notes:
+**
+** 1) The TDB date date1+date2 is a Julian Date, apportioned in any
+** convenient way between the two arguments. For example,
+** JD(TDB)=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. For most
+** applications of this function the choice will not be at all
+** critical.
+**
+** TT can be used instead of TDB without any significant impact on
+** accuracy.
+**
+** 2) All the vectors are with respect to BCRS axes.
+**
+** 3) In cases where the caller does not wish to provide the Earth
+** ephemeris and CIP/CIO, the function eraApci13 can be used instead
+** of the present function. This computes the required quantities
+** using other ERFA functions.
+**
+** 4) This is one of several functions that inserts into the astrom
+** structure star-independent parameters needed for the chain of
+** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
+**
+** The various functions support different classes of observer and
+** portions of the transformation chain:
+**
+** functions observer transformation
+**
+** eraApcg eraApcg13 geocentric ICRS <-> GCRS
+** eraApci eraApci13 terrestrial ICRS <-> CIRS
+** eraApco eraApco13 terrestrial ICRS <-> observed
+** eraApcs eraApcs13 space ICRS <-> GCRS
+** eraAper eraAper13 terrestrial update Earth rotation
+** eraApio eraApio13 terrestrial CIRS <-> observed
+**
+** Those with names ending in "13" use contemporary ERFA models to
+** compute the various ephemerides. The others accept ephemerides
+** supplied by the caller.
+**
+** The transformation from ICRS to GCRS covers space motion,
+** parallax, light deflection, and aberration. From GCRS to CIRS
+** comprises frame bias and precession-nutation. From CIRS to
+** observed takes account of Earth rotation, polar motion, diurnal
+** aberration and parallax (unless subsumed into the ICRS <-> GCRS
+** transformation), and atmospheric refraction.
+**
+** 5) The context structure astrom produced by this function is used by
+** eraAtciq* and eraAticq*.
+**
+** Called:
+** eraApcg astrometry parameters, ICRS-GCRS, geocenter
+** eraC2ixys celestial-to-intermediate matrix, given X,Y and s
+**
+** Copyright (C) 2013-2016, NumFOCUS Foundation.
+** Derived, with permission, from the SOFA library. See notes at end of file.
+*/
+{
+
+/* Star-independent astrometry parameters for geocenter. */
+ eraApcg(date1, date2, ebpv, ehp, astrom);
+
+/* CIO based BPN matrix. */
+ eraC2ixys(x, y, s, astrom->bpn);
+
+/* Finished. */
+
+}
+/*----------------------------------------------------------------------
+**
+**
+** Copyright (C) 2013-2016, NumFOCUS Foundation.
+** All rights reserved.
+**
+** This library is derived, with permission, from the International
+** Astronomical Union's "Standards of Fundamental Astronomy" library,
+** available from http://www.iausofa.org.
+**
+** The ERFA version is intended to retain identical functionality to
+** the SOFA library, but made distinct through different function and
+** file names, as set out in the SOFA license conditions. The SOFA
+** original has a role as a reference standard for the IAU and IERS,
+** and consequently redistribution is permitted only in its unaltered
+** state. The ERFA version is not subject to this restriction and
+** therefore can be included in distributions which do not support the
+** concept of "read only" software.
+**
+** Although the intent is to replicate the SOFA API (other than
+** replacement of prefix names) and results (with the exception of
+** bugs; any that are discovered will be fixed), SOFA is not
+** responsible for any errors found in this version of the library.
+**
+** If you wish to acknowledge the SOFA heritage, please acknowledge
+** that you are using a library derived from SOFA, rather than SOFA
+** itself.
+**
+**
+** TERMS AND CONDITIONS
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1 Redistributions of source code must retain the above copyright
+** notice, this list of conditions and the following disclaimer.
+**
+** 2 Redistributions in binary form must reproduce the above copyright
+** notice, this list of conditions and the following disclaimer in
+** the documentation and/or other materials provided with the
+** distribution.
+**
+** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
+** the International Astronomical Union nor the names of its
+** contributors may be used to endorse or promote products derived
+** from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+** POSSIBILITY OF SUCH DAMAGE.
+**
+*/