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rotate_c
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Procedure
Abstract
Required_Reading
Keywords
Brief_I/O
Detailed_Input
Detailed_Output
Parameters
Exceptions
Files
Particulars
Examples
Restrictions
Literature_References
Author_and_Institution
Version
Index_Entries

Procedure

   void rotate_c ( SpiceDouble     angle, 
                   SpiceInt        iaxis, 
                   SpiceDouble     mout[3][3] ) 

Abstract

 
   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. 
 

Required_Reading

 
   None. 
 

Keywords

 
   MATRIX,  ROTATION 
 

Brief_I/O

 
   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 

Detailed_Input

 
   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. 

Detailed_Output

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

Parameters

 
   None. 
 

Exceptions

 
   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. 
 

Files

 
   None. 
 

Particulars

 
   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. 
 

Examples

 
   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  | 
 

Restrictions

 
   None. 
 

Literature_References

 
   None. 
 

Author_and_Institution

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

Version

 
   -CSPICE Version 1.0.0 08-FEB-1998 (NJB)
   
      Based on SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)
      

Index_Entries

 
   generate a rotation matrix 
 
Wed Apr  5 17:54:42 2017