SUBROUTINE iau_RY ( THETA, R )
*+
*  - - - - - - -
*   i a u _ R Y
*  - - - - - - -
*
*  Rotate an r-matrix about the y-axis.
*
*  This routine is part of the International Astronomical Union's
*  SOFA (Standards of Fundamental Astronomy) software collection.
*
*  Status:  vector/matrix support routine.
*
*  Given:
*     THETA    d         angle (radians)
*
*  Given and returned:
*     R        d(3,3)    r-matrix
*
*  Sign convention:  The matrix can be used to rotate the
*  reference frame of a vector.  Calling this routine with
*  positive THETA incorporates in the matrix an additional
*  rotation, about the y-axis, anticlockwise as seen looking
*  towards the origin from positive y.
*
*  Called:
*     iau_IR       initialize r-matrix to identity
*     iau_RXR      r-matrix multiply
*     iau_CR       r-matrix copy
*
*  This revision:  2000 November 25
*
*  Copyright (C) 2001 IAU SOFA Review Board.  See notes at end.
*
*-----------------------------------------------------------------------

      IMPLICIT NONE

      DOUBLE PRECISION THETA, R(3,3)

      DOUBLE PRECISION S, C, A(3,3), W(3,3)

* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

*  Matrix representing new rotation.
      S = SIN(THETA)
      C = COS(THETA)
      CALL iau_IR ( A )
      A(1,1) = C
      A(3,1) = S
      A(1,3) = -S
      A(3,3) = C

*  Rotate.
      CALL iau_RXR ( A, R, W )

*  Return result.
      CALL iau_CR ( W, R )

*  Finished.

*+----------------------------------------------------------------------
*
*  Copyright (C) 2001
*  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. The Software is made available free of charge for use by:
*
*     a) private individuals for non-profit research; and
*
*     b) non-profit educational, academic and research institutions.
*
*  3. Commercial use of the Software is specifically excluded from the
*     terms and conditions of this license.  Commercial use of the
*     Software is subject to the prior written agreement of the Board on
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*
*  4. The provision of any version of the Software under the terms and
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*     will also be made available under the same terms and conditions.
*
*  5. The user may modify the Software for his/her own purposes.  The
*     user may distribute the modified software provided that the Board
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*     user shall be clearly identified to show how the modified software
*     differs from the original Software, and the name(s) of the
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*
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*
*  9. The Software is provided to the user "as is" and the Board makes
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*     damages, or for any claim by any third party.
*
*  Correspondence concerning SOFA software should be addressed as
*  follows:
*
*     Internet email: sofa@rl.ac.uk
*     Postal address: IAU SOFA Center
*                     Rutherford Appleton Laboratory
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*                     United Kingdom
*
*
*-----------------------------------------------------------------------

      END