rav2xf_c

Index Page rav2xf_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 rav2xf_c ( ConstSpiceDouble    rot   [3][3],
                       ConstSpiceDouble    av    [3],
                       SpiceDouble         xform [6][6]  )
#### Abstract
       This routine determines a state transformation matrix
       from a rotation matrix and the angular velocity of the
       rotation.
#### Required_Reading
       None.
#### Keywords
       FRAMES
#### Brief_I/O
       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       rot        I   Rotation matrix.
       av         I   Angular velocity vector.
       xform      O   State transformation associated with rot and av.
#### Detailed_Input
       rot         is a rotation that gives the transformation from
                   some frame frame1 to another frame frame2.

       av          is the angular velocity of the transformation.
                   In other words, if p is the position of a fixed
                   point in frame2, then from the point of view of
                   frame1,  p rotates (in a right handed sense) about
                   an axis parallel to av.  Moreover the rate of rotation
                   in radians per unit time is given by the length of
                   av.

                   More formally, the velocity v of p in frame1 is
                   given by
                                      t
                       v  = av x ( rot * p )
#### Detailed_Output
       xform       is a state transformation matrix associated
                   with rot and av.  If s1 is the state of an object
                   with respect to frame1, then the state s2 of the
                   object with respect to frame2 is given by

                       s2  =  xform * s1

                   where "*" denotes matrix-vector multiplication.
#### Parameters
       None.
#### Exceptions
       Error free.

       1) No checks are performed on ROT to ensure that it is indeed
          a rotation matrix.
#### Files
       None.
#### Particulars
       This routine is essentially a macro routine for converting
       a rotation and angular velocity of the rotation to the
       equivalent state transformation matrix.

       This routine is an inverse of xf2rav_c.
#### Examples
       Suppose that you wanted to determine state transformation
       matrix from a platform frame to the J2000 frame.

          /.
          The following call obtains the J2000-to-platform transformation
          matrix and platform angular velocity at the time of interest.
          The time value is expressed as encoded SCLK.
          ./

          ckgpav_c ( ckid, time, tol, "J2000", rot, av, &clkout, &fnd );

          /.
          Recall that rot and av are the rotation and angular velocity
          of the transformation from J2000 to the platform frame.
          ./

          if ( fnd )
          {
             /.
             First get the state transformation from J2000 to the platform
             frame.
             ./

             rav2xf_c ( rot, av, j2plt );

             /.
             Invert the state transformation matrix (using invstm_c) to
             the desired state transformation matrix.
             ./

             invstm_c ( j2plt, xform );
          }
#### Restrictions
       None.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman    (JPL)
       W.L. Taber      (JPL)
#### Version
       -CSPICE Version 1.0.1, 12-APR-2007 (EDW)

          Edit to abstract.

       -CSPICE Version 1.0.0, 18-JUN-1999 (WLT) (NJB)
#### Index_Entries
      State transformation to rotation and angular velocity
#### Link to routine rav2xf_c source file rav2xf_c.c

    Thu Apr 16 08:58:55 2009