.help euler Jun99 "Slalib Package"
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      SUBROUTINE slEULR (ORDER, PHI, THETA, PSI, RMAT)

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      E U L R
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  Form a rotation matrix from the Euler angles - three successive
  rotations about specified Cartesian axes (single precision)

  Given:
    ORDER  c*(*)    specifies about which axes the rotations occur
    PHI    r        1st rotation (radians)
    THETA  r        2nd rotation (   "   )
    PSI    r        3rd rotation (   "   )

  Returned:
    RMAT   r(3,3)   rotation matrix

  A rotation is positive when the reference frame rotates
  anticlockwise as seen looking towards the origin from the
  positive region of the specified axis.

  The characters of ORDER define which axes the three successive
  rotations are about.  A typical value is 'ZXZ', indicating that
  RMAT is to become the direction cosine matrix corresponding to
  rotations of the reference frame through PHI radians about the
  old Z-axis, followed by THETA radians about the resulting X-axis,
  then PSI radians about the resulting Z-axis.

  The axis names can be any of the following, in any order or
  combination:  X, Y, Z, uppercase or lowercase, 1, 2, 3.  Normal
  axis labeling/numbering conventions apply;  the xyz (=123)
  triad is right-handed.  Thus, the 'ZXZ' example given above
  could be written 'zxz' or '313' (or even 'ZxZ' or '3xZ').  ORDER
  is terminated by length or by the first unrecognized character.

  Fewer than three rotations are acceptable, in which case the later
  angle arguments are ignored.  If all rotations are zero, the
  identity matrix is produced.

  Called:  slDEUL

  P.T.Wallace   Starlink   23 May 1997

  Copyright (C) 1997 Rutherford Appleton Laboratory
  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.

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