Index Page rotate_c

A B C D E F G H I J K L M N O P Q R S T U V W X

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

#### Link to routine rotate_c source file rotate_c.c

    Wed Apr  5 17:54:42 2017