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cspice_rotvec

Table of contents
Abstract
I/O
Parameters
Examples
Particulars
Exceptions
Files
Restrictions
Required_Reading
Literature_References
Author_and_Institution
Version
Index_Entries


Abstract


   CSPICE_ROTVEC transforms a vector to a new reference frame rotated by
   `angle' radians about axis `iaxis'. This transformation rotates `v1' by
   -angle radians about the specified axis.

I/O


   Given:

      v1       a vector (typically representing a vector fixed in inertial
               space) which is to be expressed in another reference frame.

               help, v1
                  DOUBLE = Array[3]

               The vector remains fixed but the reference frame changes.

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

               help, angle
                  DOUBLE = Scalar

      iaxis    the index of the axis of rotation.

               help, iaxis
                  LONG = Scalar

               The X, Y, and Z axes have indices 1, 2 and 3 respectively.

   the call:

      cspice_rotvec, v1, angle, iaxis, vout

   returns:

      vout     the vector expressed in the new reference frame specified by the
               angle of rotation and axis.

               help, vout
                  DOUBLE = Array[3]

               If

                  m = [angle]
                             iaxis

               represents the rotation matrix described by the `angle'
               and `iaxis', (refer to the routine cspice_rotate) then

                  vout =  m * v1  = [angle]      * v1
                                           iaxis

Parameters


   None.

Examples


   Any numerical results shown for this example may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

   1) Apply a rotation of -45.D0 degrees about the +Z axis to
      a 3 dimensional vector.

      Example code begins here.


      PRO rotvec_ex1

         ;;
         ;; Input values.
         ;;
         v1 = [1.414, 0.0, 0.0]

         angle = cspice_pi( )/4
         iaxis = 3

         ;;
         ;; Rotate V1 by ANGLE radians about IAXIS
         ;;
         cspice_rotvec, v1, angle, iaxis, vout

         print, format='(A,3F10.3)', 'Input vector  :', $
                                   v1[0], v1[1], v1[2]
         print, format='(A,3F10.3)', 'Rotated vector:', $
                             vout[0], vout[1], vout[2]

      END


      When this program was executed on a Mac/Intel/IDL8.x/64-bit
      platform, the output was:


      Input vector  :     1.414     0.000     0.000
      Rotated vector:     1.000    -1.000     0.000


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)  1   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   |
      `-                            -'

   cspice_rotvec decides which form is appropriate according to the value
   of `iaxis' and applies the rotation to the input vector.

Exceptions


   1)  If the `iaxis' 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.

   2)  If any of the input arguments, `v1', `angle' or `iaxis', is
       undefined, an error is signaled by the IDL error handling
       system.

   3)  If any of the input arguments, `v1', `angle' or `iaxis', is
       not of the expected type, or it does not have the expected
       dimensions and size, an error is signaled by the Icy
       interface.

   4)  If the output argument `vout' is not a named variable, an
       error is signaled by the Icy interface.

Files


   None.

Restrictions


   None.

Required_Reading


   ICY.REQ
   ROTATION.REQ

Literature_References


   None.

Author_and_Institution


   J. Diaz del Rio     (ODC Space)
   E.D. Wright         (JPL)

Version


   -Icy Version 1.0.2, 10-AUG-2021 (JDR)

       Edited the header to comply with NAIF standard. Added complete code
       example.

       Added -Parameters, -Particulars, -Exceptions, -Files, -Restrictions,
       -Literature_References and -Author_and_Institution sections.

       Removed reference to the routine's corresponding CSPICE header from
       -Abstract section and improved its contents.

       Added arguments' type and size information in the -I/O section.

   -Icy Version 1.0.1, 09-DEC-2005 (EDW)

       Added -Examples section.

   -Icy Version 1.0.0, 16-JUN-2003 (EDW)

Index_Entries


   rotate a vector



Fri Dec 31 18:43:07 2021