#include "sofam.h"
 
void iauPfw06(double date1, double date2,
              double *gamb, double *phib, double *psib, double *epsa)
/*
**  - - - - - - - - -
**   i a u P f w 0 6
**  - - - - - - - - -
**
**  Precession angles, IAU 2006 (Fukushima-Williams 4-angle formulation).
**
**  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:
**     gamb         double   F-W angle gamma_bar (radians)
**     phib         double   F-W angle phi_bar (radians)
**     psib         double   F-W angle psi_bar (radians)
**     epsa         double   F-W angle epsilon_A (radians)
**
**  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) Naming the following points:
**
**           e = J2000 ecliptic pole,
**           p = GCRS pole,
**           E = mean ecliptic pole of date,
**     and   P = mean pole of date,
**
**     the four Fukushima-Williams angles are as follows:
**
**        gamb = gamma_bar = epE
**        phib = phi_bar = pE
**        psib = psi_bar = pEP
**        epsa = epsilon_A = EP
**
**  3) The matrix representing the combined effects of frame bias and
**     precession is:
**
**        PxB = R_1(-epsa).R_3(-psib).R_1(phib).R_3(gamb)
**
**  4) The matrix representing the combined effects of frame bias,
**     precession and nutation is simply:
**
**        NxPxB = R_1(-epsa-dE).R_3(-psib-dP).R_1(phib).R_3(gamb)
**
**     where dP and dE are the nutation components with respect to the
**     ecliptic of date.
**
**  Reference:
**
**     Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351
**
**  Called:
**     iauObl06     mean obliquity, IAU 2006
**
**  This revision:  2008 May 24
**
**  Copyright (C) 2008 IAU SOFA Review Board.  See notes at end.
*/
{
   double t;


/* Interval between fundamental date J2000.0 and given date (JC). */
   t = ((date1 - DJ00) + date2) / DJC;
 
/* P03 bias+precession angles. */
   *gamb = (    -0.052928     +
           (    10.556378     +
           (     0.4932044    +
           (    -0.00031238   +
           (    -0.000002788  +
           (     0.0000000260 )
           * t) * t) * t) * t) * t) * DAS2R;
   *phib = ( 84381.412819     +
           (   -46.811016     +
           (     0.0511268    +
           (     0.00053289   +
           (    -0.000000440  +
           (    -0.0000000176 )
           * t) * t) * t) * t) * t) * DAS2R;
   *psib = (    -0.041775     +
           (  5038.481484     +
           (     1.5584175    +
           (    -0.00018522   +
           (    -0.000026452  +
           (    -0.0000000148 )
           * t) * t) * t) * t) * t) * DAS2R;
   *epsa =  iauObl06(date1, date2);
 
   return;

/*-----------------------------------------------------------------------
**
**  Copyright (C) 2008
**  Standards Of Fundamental Astronomy Review Board
**  of the International Astronomical Union.
**
**  =====================
**  SOFA Software License
**  =====================
**
**  NOTICE TO USER:
**
**  BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING TERMS AND CONDITIONS
**  WHICH APPLY TO ITS USE.
**
**  1. The Software is owned by the IAU SOFA Review Board ("the Board").
**
**  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 adapt the SOFA software and its 
**     algorithms for your own purposes and you may copy and distribute
**     a resulting "derived work" to others on a world-wide, royalty-free 
**     basis, provided that the derived work complies with the following
**     requirements: 
**
**     a) Your work shall be marked or carry a statement that it (i) uses
**        routines and computations derived by you from software provided 
**        by SOFA under license to you; and (ii) does not contain
**        software provided by SOFA or software that has been distributed
**        by or endorsed by SOFA.
**
**     b) The source code of your derived work must contain descriptions
**        of how the derived work is based upon and/or differs from the
**        original SOFA software.
**
**     c) The name(s) of all routine(s) that you distribute shall differ
**        from the SOFA names, even when the SOFA content has not been
**        otherwise changed.
**
**     d) The routine-naming prefix "iau" shall not be used.
**
**     e) The origin of the SOFA components of your derived work must not
**        be misrepresented;  you must not claim that you wrote the
**        original software, nor file a patent application for SOFA
**        software or algorithms embedded in the SOFA software.
**
**     f) These requirements must be reproduced intact in any source
**        distribution and shall apply to anyone to whom you have granted 
**        a further right to modify the source code of your derived work.
**
**  4. In any published work or commercial products which includes
**     results achieved by using the SOFA software, you shall acknowledge
**     that the SOFA software was used in obtaining those results.
**
**  5. You shall not cause the SOFA software to be brought into
**     disrepute, either by misuse, or use for inappropriate tasks, or by
**     inappropriate modification.
**
**  6. The SOFA software is provided "as is" and the Board makes no 
**     warranty as to its use or performance.   The Board does not and 
**     cannot warrant the performance or results which the user may obtain 
**     by using the SOFA software.  The Board makes no warranties, express 
**     or implied, as to non-infringement of third party rights,
**     merchantability, or fitness for any particular purpose.  In no
**     event will the Board be liable to the user for any consequential,
**     incidental, or special damages, including any lost profits or lost
**     savings, even if a Board representative has been advised of such
**     damages, or for any claim by any third party.
**
**  7. The provision of any version of the SOFA software under the terms 
**     and conditions specified herein does not imply that future
**     versions will also be made available under the same terms and
**     conditions.
**
**  Correspondence concerning SOFA software should be addressed as
**  follows:
**
**     Internet email: sofa@rl.ac.uk
**     Postal address: IAU SOFA Center
**                     Rutherford Appleton Laboratory
**                     Chilton, Didcot, Oxon OX11 0QX
**                     United Kingdom
**
**---------------------------------------------------------------------*/
}