Procedure

     SPKE03 ( S/P Kernel, evaluate, type 3 )

     SUBROUTINE SPKE03 ( ET, RECORD, STATE )

Abstract

     Evaluate a single SPK data record from a segment of type 3
     (Chebyshev Polynomials, position and velocity).

Required_Reading

     SPK

Keywords

     EPHEMERIS

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION      ET
     DOUBLE PRECISION      RECORD   ( * )
     DOUBLE PRECISION      STATE    ( 6 )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     ET         I   Evaluation epoch.
     RECORD     I   Data record.
     STATE      O   State (position and velocity).

Detailed_Input

     ET       is the epoch at which a state vector or Euler angle
              state is to be computed. The epoch is represented as
              seconds past J2000 TDB.

     RECORD   is a data record which, when evaluated at epoch ET,
              will yield three function components and their
              derivatives with respect to time. The record
              structure for SPK type 3 data is:

                 +--------------------------------------+
                 | record size (excluding this element) |
                 +--------------------------------------+
                 | Coverage interval midpoint           |
                 +--------------------------------------+
                 | Coverage interval radius             |
                 +--------------------------------------+
                 | Coeffs for X position component      |
                 +--------------------------------------+
                 | Coeffs for Y position component      |
                 +--------------------------------------+
                 | Coeffs for Z position component      |
                 +--------------------------------------+
                 | Coeffs for X velocity component      |
                 +--------------------------------------+
                 | Coeffs for Y velocity component      |
                 +--------------------------------------+
                 | Coeffs for Z velocity component      |
                 +--------------------------------------+

              In the above record

                 - Times are expressed as seconds past J2000 TDB.
                 - Position components have units of km.
                 - Velocity components have units of km/s.

              RECORD must be declared by the caller with size large
              enough to accommodate the largest record that can be
              returned by this routine. See the INCLUDE file
              spkrec.inc for the correct record length.

Detailed_Output

     STATE    is the state. In order, X, Y, Z, X', Y', and Z'.
              Units are km and km/sec.

Parameters

     None.

Exceptions

     1)  If the input record contains an invalid coefficient count,
         the error SPICE(INVALIDCOUNT) is signaled.

     2)  If the input record contains invalid domain transformation
         parameters, an error is signaled by a routine in the
         call tree of this routine.

Files

     None.

Particulars

     The exact format and structure of type 3 (Chebyshev polynomials,
     position and velocity) segments are described in the SPK
     Required Reading file.

     A type 3 segment contains six sets of Chebyshev coefficients,
     one set each for the position coordinates X, Y, and Z, and one
     set each for the velocity coordinates X', Y', and Z'.  SPKE03
     calls the routine CHBVAL to evaluate each polynomial, and arrive
     at the complete state.

Examples

     The SPKEnn routines are almost always used in conjunction with
     the corresponding SPKRnn routines, which read the records from
     SPK files.

     The data returned by the SPKRnn 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 SPKRnn
     routines might be used to examine raw segment data before
     evaluating it with the SPKEnn routines.


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

     C
     C     Look at parts of the descriptor.
     C
           CALL DAFUS ( DESCR, 2, 6, DCD, ICD )
           CENTER = ICD( 2 )
           REF    = ICD( 3 )
           TYPE   = ICD( 4 )

           IF ( TYPE .EQ. 3 ) THEN

              CALL SPKR03 ( HANDLE, DESCR, ET, RECORD )
                  .
                  .  Look at the RECORD data.
                  .
              CALL SPKE03 ( ET, RECORD, STATE )
                  .
                  .  Check out the evaluated state.
                  .
           END IF

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     H.A. Neilan        (JPL)
     W.L. Taber         (JPL)
     R.E. Thurman       (JPL)

Version

    SPICELIB Version 2.1.0, 14-APR-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard. Moved SPK
        required reading from $Literature_References to
        $Required_Reading section.

    SPICELIB Version 2.0.0, 31-DEC-2013 (NJB)

        Added error checks for invalid coefficient counts
        and invalid interval radius. Changed error handling
        style to "discovery." Enhanced header documentation.

    SPICELIB Version 1.0.3, 10-MAR-1992 (WLT)

        Comment section for permuted index source lines was added
        following the header.

    SPICELIB Version 1.0.2, 23-AUG-1991 (HAN)

        SPK03 was removed from the $Required_Reading section of the
        header. The information in the SPK03 Required Reading file
        is now part of the SPK Required Reading file.

    SPICELIB Version 1.0.1, 22-MAR-1990 (HAN)

        Literature references added to the header.

    SPICELIB Version 1.0.0, 31-JAN-1990 (RET)