pn00.c

Go to the documentation of this file.

#include "erfa.h"

void eraPn00(double date1, double date2, double dpsi, double deps,
             double *epsa,
             double rb[3][3], double rp[3][3], double rbp[3][3],
             double rn[3][3], double rbpn[3][3])
/*
**  - - - - - - - -
**   e r a P n 0 0
**  - - - - - - - -
**
**  Precession-nutation, IAU 2000 model:  a multi-purpose function,
**  supporting classical (equinox-based) use directly and CIO-based
**  use indirectly.
**
**  Given:
**     date1,date2  double          TT as a 2-part Julian Date (Note 1)
**     dpsi,deps    double          nutation (Note 2)
**
**  Returned:
**     epsa         double          mean obliquity (Note 3)
**     rb           double[3][3]    frame bias matrix (Note 4)
**     rp           double[3][3]    precession matrix (Note 5)
**     rbp          double[3][3]    bias-precession matrix (Note 6)
**     rn           double[3][3]    nutation matrix (Note 7)
**     rbpn         double[3][3]    GCRS-to-true matrix (Note 8)
**
**  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 caller is responsible for providing the nutation components;
**     they are in longitude and obliquity, in radians and are with
**     respect to the equinox and ecliptic of date.  For high-accuracy
**     applications, free core nutation should be included as well as
**     any other relevant corrections to the position of the CIP.
**
**  3) The returned mean obliquity is consistent with the IAU 2000
**     precession-nutation models.
**
**  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) It is permissible to re-use the same array in the returned
**     arguments.  The arrays are filled in the order given.
**
**  Called:
**     eraPr00      IAU 2000 precession adjustments
**     eraObl80     mean obliquity, IAU 1980
**     eraBp00      frame bias and precession matrices, IAU 2000
**     eraCr        copy r-matrix
**     eraNumat     form nutation matrix
**     eraRxr       product of two r-matrices
**
**  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.
**
**  Copyright (C) 2013-2015, NumFOCUS Foundation.
**  Derived, with permission, from the SOFA library.  See notes at end of file.
*/
{
   double dpsipr, depspr, rbpw[3][3], rnw[3][3];

/* IAU 2000 precession-rate adjustments. */
   eraPr00(date1, date2, &dpsipr, &depspr);

/* Mean obliquity, consistent with IAU 2000 precession-nutation. */
   *epsa = eraObl80(date1, date2) + depspr;

/* Frame bias and precession matrices and their product. */
   eraBp00(date1, date2, rb, rp, rbpw);
   eraCr(rbpw, rbp);

/* Nutation matrix. */
   eraNumat(*epsa, dpsi, deps, rnw);
   eraCr(rnw, rn);

/* Bias-precession-nutation matrix (classical). */
   eraRxr(rnw, rbpw, rbpn);

   return;

}
/*----------------------------------------------------------------------
**  
**  
**  Copyright (C) 2013-2015, 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.
**  
*/