Calculate the 3x3 rotation matrix generated by a rotation 
   of a specified angle about a specified axis. This rotation 
   is thought of as rotating the coordinate system. 

   None. 

   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   angle      I   Angle of rotation (radians). 
   iaxis      I   Axis of rotation (X=1, Y=2, Z=3). 
   mout       O   Resulting rotation matrix [angle] 
                                                   iaxis 

   angle   The angle given in radians, through which the rotation 
           is performed. 

   iaxis   The index of the axis of rotation.  The X, Y, and Z 
           axes have indices 1, 2 and 3 respectively. 

   mout    Rotation matrix which describes the rotation of the 
           COORDINATE system through angle radians about the 
           axis whose index is iaxis. 

   None. 

   A rotation about the first, i.e. x-axis, is described by 

      |  1        0          0      | 
      |  0   cos(theta) sin(theta)  | 
      |  0  -sin(theta) cos(theta)  | 

   A rotation about the second, i.e. y-axis, is described by 

      |  cos(theta)  0  -sin(theta)  | 
      |      0       1        0      | 
      |  sin(theta)  0   cos(theta)  | 

   A rotation about the third, i.e. z-axis, is described by 

      |  cos(theta) sin(theta)   0   | 
      | -sin(theta) cos(theta)   0   | 
      |       0          0       1   | 

   rotate_c decides which form is appropriate according to the value 
   of IAXIS. 

   If rotate_c is called from a C program as follows: 

         rotate_c ( pi_c()/4, 3, mout ); 

   then mout will be given by 

                | sqrt(2)/2   sqrt(2)/2   0  | 
         mout = |-sqrt(2)/2   sqrt(2)/2   0  | 
                |     0           0       1  | 

   None. 

   Error free. 

   1) If the axis index is not in the range 1 to 3 it will be 
      treated the same as that integer 1, 2, or 3 that is congruent 
      to it mod 3. 

   None. 

   N.J. Bachman    (JPL)
   W.M. Owen       (JPL) 
   W.L. Taber      (JPL) 

   None. 

   -CSPICE Version 1.0.0 08-FEB-1998 (NJB)

      Based on SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)

   generate a rotation matrix