Procedure

     SPKS18 ( S/P Kernel, subset, type 18 )

     SUBROUTINE SPKS18 ( HANDLE, BADDR, EADDR, BEGIN, END )

Abstract

     Extract a subset of the data in an SPK segment of type 18
     into a new segment.

Required_Reading

     SPK
     DAF

Keywords

     EPHEMERIS

Declarations

     IMPLICIT NONE

     INCLUDE 'spk18.inc'

     INTEGER               HANDLE
     INTEGER               BADDR
     INTEGER               EADDR
     DOUBLE PRECISION      BEGIN
     DOUBLE PRECISION      END

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   Handle of file containing source segment.
     BADDR      I   Beginning address in file of source segment.
     EADDR      I   Ending address in file of source segment.
     BEGIN      I   Beginning (initial epoch) of subset.
     END        I   End (final epoch) of subset.

Detailed_Input

     HANDLE,
     BADDR,
     EADDR    are the file handle assigned to an SPK file, and the
              beginning and ending addresses of a segment within
              that file. Together they determine a complete set of
              ephemeris data, from which a subset is to be
              extracted.

     BEGIN,
     END      are the initial and final epochs (ephemeris time)
              of the subset.

              The first epoch for which there will be ephemeris
              data in the new segment will be the greatest time
              in the source segment that is less than or equal
              to BEGIN.

              The last epoch for which there will be ephemeris
              data in the new segment will be the smallest time
              in the source segment that is greater than or equal
              to END.

Detailed_Output

     See $Files section.

Parameters

     None.

Exceptions

     1)  This routine relies on the caller to ensure that the
         interval [BEGIN, END] is contained in the coverage
         interval of the segment.

     2)  If BEGIN > END, no data are written to the target file.

     3)  If an unexpected SPK type 18 subtype is found in the input
         segment, the error SPICE(INVALIDVALUE) is signaled.

Files

     Data are extracted from the file connected to the input
     handle, and written to the current DAF open for writing.

     The segment descriptor and summary must already have been written
     prior to calling this routine. The segment must be ended
     external to this routine.

Particulars

     This routine is intended solely for use as a utility by the
     routine SPKSUB.

     It transfers a subset of a type 18 SPK data segment to
     a properly initialized segment of a second SPK file.

     The exact structure of a segment of data type 18 is described
     in the section on type 18 in the SPK Required Reading.

Examples

     This routine is intended only for use as a utility by SPKSUB.
     To use this routine successfully, you must:

        Open the SPK file from which to extract data.
        Locate the segment from which data should be extracted.

        Open the SPK file to which this data should be written.
        Begin a new segment (array).
        Write the summary information for the array.

        Call this routine to extract the appropriate data from the
        SPK open for read.

        End the array to which this routine writes data.

     Much of this procedure is carried out by the routine SPKSUB. The
     examples of that routine illustrate more fully the process
     described above.

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)

Version

    SPICELIB Version 1.1.1, 03-JUN-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.1.0, 22-DEC-2012 (NJB)

        Bug fix: code applicable to SPK type 9 for
        creating padding in the output segment was
        deleted.

    SPICELIB Version 1.0.0, 16-AUG-2002 (NJB) (WLT) (IMU)