Procedure

     PCKE03 ( PCK, evaluate data record from type 3 segment )

     SUBROUTINE PCKE03 ( ET, RECORD, ROTMAT )

Abstract

     Evaluate a single PCK data record from a segment of type 03
     (Variable width Chebyshev Polynomials for RA, DEC, and W) to
     obtain a state transformation matrix.

Required_Reading

     PCK

Keywords

     PCK

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION      ET
     DOUBLE PRECISION      RECORD   ( *    )
     DOUBLE PRECISION      ROTMAT   ( 6, 6 )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     ET         I   Target epoch state transformation.
     RECORD     I   Data record valid for epoch ET.
     ROTMAT     O   State transformation matrix at epoch ET.

Detailed_Input

     ET       is a target epoch, at which a state transformation
              matrix is to be calculated.

     RECORD   is a data record which, when evaluated at epoch ET,
              will give RA, DEC, and W and angular velocity
              for a body. The RA, DEC and W are relative to
              some inertial frame. The angular velocity is
              expressed relative to the body fixed coordinate frame.

Detailed_Output

     ROTMAT   is the state transformation matrix at epoch ET.

Parameters

     None.

Exceptions

     None.

Files

     None.

Particulars

     The exact format and structure of type 03 PCK segments are
     described in the PCK Required Reading file.

     A type 03 segment contains six sets of Chebyshev coefficients,
     one set each for RA, DEC, and W and one set each for the
     components of the angular velocity of the body. The coefficients
     for RA, DEC, and W are relative to some inertial reference
     frame. The coefficients for the components of angular velocity
     are relative to the body fixed frame and must be transformed
     via the position transformation corresponding to RA, DEC and W.

     PCKE03 calls the routine CHBVAL to evaluate each polynomial,
     to obtain a complete set of values. These values are then
     used to determine a state transformation matrix that will
     rotate an inertially referenced state into the bodyfixed
     coordinate system.

Examples

     The PCKEnn routines are almost always used in conjunction with
     the corresponding PCKRnn routines, which read the records from
     binary PCK files.

     The data returned by the PCKRnn routine is in its rawest form,
     taken directly from the segment. As such, it will be meaningless
     to a user unless he/she understands the structure of the data type
     completely. Given that understanding, however, the PCKRnn
     routines might be used to examine raw segment data before
     evaluating it with the PCKEnn routines.


     C
     C     Get a segment applicable to a specified body and epoch.
     C
           CALL PCKSFS ( BODY, ET, HANDLE, DESCR, IDENT, FOUND )

     C
     C     Look at parts of the descriptor.
     C
           CALL DAFUS ( DESCR, 2, 6, DCD, ICD )
           TYPE   = ICD( 3 )

           IF ( TYPE .EQ. 03 ) THEN

              CALL PCKR03 ( HANDLE, DESCR, ET, RECORD )
                  .
                  .  Look at the RECORD data.
                  .
              CALL PCKE03 ( ET, RECORD, ROTMAT )
                  .
                  .  Apply the rotation and check out the state.
                  .
           END IF

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     K.R. Gehringer     (JPL)
     W.L. Taber         (JPL)
     E.D. Wright        (JPL)

Version

    SPICELIB Version 3.0.2, 20-AUG-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 3.0.1, 03-JAN-2014 (EDW)

        Minor edits to $Procedure; clean trailing whitespace.
        Removed unneeded $Revisions section.

    SPICELIB Version 3.0.0, 06-OCT-1995 (WLT)

        Brian Carcich at Cornell discovered that the Euler
        angles were being re-arranged unnecessarily. As a
        result the state transformation matrix computed was
        not the one we expected. (The re-arrangement was
        a left-over from  implementation 1.0.0. This problem
        has now been corrected.

    SPICELIB Version 2.0.0, 28-JUL-1995 (WLT)

        Version 1.0.0 was written under the assumption that
        RA, DEC, W and dRA/dt, dDEC/dt and dW/dt were supplied
        in the input RECORD. This version repairs the
        previous misinterpretation.

    SPICELIB Version 1.0.0, 14-MAR-1995 (KRG)