#include "sofam.h"

void iauPom00(double xp, double yp, double sp, double rpom[3][3])
/*
**  - - - - - - - - - -
**   i a u P o m 0 0
**  - - - - - - - - - -
**
**  Form the matrix of polar motion for a given date, IAU 2000.
**
**  This function is part of the International Astronomical Union's
**  SOFA (Standards Of Fundamental Astronomy) software collection.
**
**  Status:  support function.
**
**  Given:
**     xp,yp    double    coordinates of the pole (radians, Note 1)
**     sp       double    the TIO locator s' (radians, Note 2)
**
**  Returned:
**     rpom     double[3][3]   polar-motion matrix (Note 3)
**
**  Notes:
**
**  1) The arguments xp and yp are the coordinates (in radians) of the
**     Celestial Intermediate Pole with respect to the International
**     Terrestrial Reference System (see IERS Conventions 2003),
**     measured along the meridians to 0 and 90 deg west respectively.
**
**  2) The argument sp is the TIO locator s', in radians, which
**     positions the Terrestrial Intermediate Origin on the equator.  It
**     is obtained from polar motion observations by numerical
**     integration, and so is in essence unpredictable.  However, it is
**     dominated by a secular drift of about 47 microarcseconds per
**     century, and so can be taken into account by using s' = -47*t,
**     where t is centuries since J2000.0.  The function iauSp00
**     implements this approximation.
**
**  3) The matrix operates in the sense V(TRS) = rpom * V(CIP), meaning
**     that it is the final rotation when computing the pointing
**     direction to a celestial source.
**
**  Called:
**     iauIr        initialize r-matrix to identity
**     iauRz        rotate around Z-axis
**     iauRy        rotate around Y-axis
**     iauRx        rotate around X-axis
**
**  Reference:
**
**     McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
**     IERS Technical Note No. 32, BKG (2004)
**
**  This revision:  2009 December 17
**
**  SOFA release 2009-12-31
**
**  Copyright (C) 2009 IAU SOFA Review Board.  See notes at end.
*/
{

/* Construct the matrix. */
   iauIr(rpom);
   iauRz(sp, rpom);
   iauRy(-xp, rpom);
   iauRx(-yp, rpom);

   return;

/*----------------------------------------------------------------------
**
**  Copyright (C) 2009
**  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 ("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,
**     on a world-wide, royalty-free basis.  That portion of your
**     distribution that does not consist of intact and unchanged copies
**     of SOFA source code files is a "derived work" that must comply
**     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
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**        endorsed by SOFA.
**
**     b) The source code of your derived work must contain descriptions
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**
**     c) The name(s) of all routine(s) in your derived work shall not
**        include the prefix "iau_".
**
**     d) The origin of the SOFA components of your derived work must
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**
**     e) These requirements must be reproduced intact in any source
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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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**
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**
**  Correspondence concerning SOFA software should be addressed as
**  follows:
**
**      By email:  sofa@rl.ac.uk
**      By post:   IAU SOFA Center
**                 STFC Rutherford Appleton Laboratory
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**                 United Kingdom
**
**--------------------------------------------------------------------*/
}