iau_RY.f90

      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) 2003 IAU SOFA Review Board.  See notes at end.
!
!-----------------------------------------------------------------------

      IMPLICIT NONE

      REAL*8 THETA, R(3,3)

      REAL*8 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) 2003
!  Standards Of Fundamental Astronomy Review Board
!  of the International Astronomical Union.
!
!  =====================
!  SOFA Software License
!  =====================
!
!  NOTICE TO USER:
!
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!  WHICH APPLY TO ITS USE.
!
!  1. The Software is owned by the IAU SOFA Review Board ("the Board").
!
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!
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!
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!
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!
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!
!-----------------------------------------------------------------------

      END