ry.c

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#include "erfa.h"

void eraRy(double theta, double r[3][3])
/*
**  - - - - - -
**   e r a R y
**  - - - - - -
**
**  Rotate an r-matrix about the y-axis.
**
**  Given:
**     theta  double          angle (radians)
**
**  Given and returned:
**     r      double[3][3]    r-matrix, rotated
**
**  Notes:
**
**  1) Calling this function with positive theta incorporates in the
**     supplied r-matrix r an additional rotation, about the y-axis,
**     anticlockwise as seen looking towards the origin from positive y.
**
**  2) The additional rotation can be represented by this matrix:
**
**         (  + cos(theta)     0      - sin(theta)  )
**         (                                        )
**         (       0           1           0        )
**         (                                        )
**         (  + sin(theta)     0      + cos(theta)  )
**
**  Copyright (C) 2013-2015, NumFOCUS Foundation.
**  Derived, with permission, from the SOFA library.  See notes at end of file.
*/
{
   double s, c, a00, a01, a02, a20, a21, a22;

   s = sin(theta);
   c = cos(theta);

   a00 = c*r[0][0] - s*r[2][0];
   a01 = c*r[0][1] - s*r[2][1];
   a02 = c*r[0][2] - s*r[2][2];
   a20 = s*r[0][0] + c*r[2][0];
   a21 = s*r[0][1] + c*r[2][1];
   a22 = s*r[0][2] + c*r[2][2];

   r[0][0] = a00;
   r[0][1] = a01;
   r[0][2] = a02;
   r[2][0] = a20;
   r[2][1] = a21;
   r[2][2] = a22;

   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
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**    distribution.
**  
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*/