Procedure

     SPKR08 ( Read SPK record from segment, type 8 )

     SUBROUTINE SPKR08 ( HANDLE, DESCR, ET, RECORD )

Abstract

     Read a single SPK data record from a segment of type 8
     (equally spaced discrete states, interpolated by Lagrange
     polynomials).

Required_Reading

     SPK
     TIME

Keywords

     EPHEMERIS

Declarations

     IMPLICIT NONE

     INTEGER               HANDLE
     DOUBLE PRECISION      DESCR    ( 5 )
     DOUBLE PRECISION      ET
     DOUBLE PRECISION      RECORD   ( * )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   File handle.
     DESCR      I   Segment descriptor.
     ET         I   Target epoch.
     RECORD     O   Data record.

Detailed_Input

     HANDLE,
     DESCR    are the file handle and segment descriptor for
              a SPK segment of type 8.

     ET       is a target epoch, for which a data record from
              a specific segment is required.

Detailed_Output

     RECORD   is a set of data from the specified 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.

              The structure of the record is as follows:

                 +----------------------+
                 | number of states (n) |
                 +----------------------+
                 | start epoch          |
                 +----------------------+
                 | step size            |
                 +----------------------+
                 | state 1 (6 elts.)    |
                 +----------------------+
                 | state 2 (6 elts.)    |
                 +----------------------+
                             .
                             .
                             .
                 +----------------------+
                 | state n (6 elts.)    |
                 +----------------------+

Parameters

     None.

Exceptions

     This routine follows the pattern established in the lower-numbered
     SPK data type readers of not explicitly performing error
     diagnoses. Exceptions are listed below nonetheless.

     1)  If the input HANDLE does not designate a loaded SPK file, an
         error is signaled by a routine in the call tree of this
         routine.

     2)  If the segment specified by DESCR is not of data type 08,
         the error SPICE(WRONGSPKTYPE) is signaled.

     3)  If the input ET value is not within the range specified
         in the segment descriptor, the error SPICE(TIMEOUTOFBOUNDS)
         is signaled.

Files

     See argument HANDLE.

Particulars

     See the SPK Required Reading file for a description of the
     structure of a data type 8 segment.

Examples

     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 SPKRxx
     routines might be used to "dump" and check segment data for a
     particular epoch.


     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. 8 ) THEN
              CALL SPKR08 ( HANDLE, DESCR, ET, RECORD )
                  .
                  .  Look at the RECORD data.
                  .
           END IF

Restrictions

     1)  Correctness of inputs must be ensured by the caller of
         this routine.

Literature_References

     None.

Author_and_Institution

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

Version

    SPICELIB Version 2.1.1, 12-AUG-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 2.1.0, 07-SEP-2001 (EDW)

        Replaced DAFRDA call with DAFGDA.
        Added IMPLICIT NONE.

    SPICELIB Version 2.0.0, 06-NOV-1999 (NJB)

        Data type check was relaxed to enable reading type 12
        segments.

    SPICELIB Version 1.0.1, 24-OCT-1994 (NJB)

        In-line comment concerning transpose of state data was
        removed.

    SPICELIB Version 1.0.0, 14-AUG-1993 (NJB)