Procedure

     SPKE14 ( S/P Kernel, evaluate, type 14 )

     SUBROUTINE SPKE14 ( ET, RECORD, STATE )

Abstract

     Evaluate a single data record from a type 14 SPK segment.

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   Epoch for which a state is desired.
     RECORD     I   Record from a type 14 SPK segment valid for ET.
     STATE      O   State (position and velocity) at epoch ET.

Detailed_Input

     ET       is the epoch for which a state vector is desired.

     RECORD   is a record from a type 14 SPK segment which, when
              evaluated at epoch ET, will give the state (position
              and velocity) of some body, relative to some center, in
              some inertial reference frame.

Detailed_Output

     STATE    is the state vector at epoch ET. Its contents are, in
              order, X, Y, Z, X', Y', and Z'. Units are km and km/sec.

Parameters

     None.

Exceptions

     None.

Files

     None.

Particulars

     The exact format and structure of a type 14 SPK segment is
     described in the SPK Required Reading.

     A type 14 record 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' of a state
     vector.  SPKE14 calls the routine CHBVAL to evaluate each
     Chebyshev 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 a raw form, taken
     directly from the segment. As such, it will be not be directly
     useful to a user unless they have a complete understanding of the
     structure of the data type. Given that understanding, however,
     the SPKRnn routines could be used to "dump" and check segment data
     for a particular epoch before evaluating the record to obtain a
     state vector, as in the example which follows.


     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. 14 ) THEN

              CALL SPKR14 ( HANDLE, DESCR, ET, RECORD )
                  .
                  .  Look at the RECORD data.
                  .
              CALL SPKE14 ( ET, RECORD, STATE )
                  .
                  .  Check out the evaluated state.
                  .
           END IF

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     K.R. Gehringer     (JPL)

Version

    SPICELIB Version 1.0.1, 17-JUN-2021 (JDR)

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

    SPICELIB Version 1.0.0, 10-MAR-1995 (KRG)