Index Page spksfs_c

A B C D E F G H I J K L M N O P Q R S T U V W X

Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       void spksfs_c ( SpiceInt        body,
                       SpiceDouble     et,
                       SpiceInt        idlen,
                       SpiceInt      * handle,
                       SpiceDouble     descr [5],
                       SpiceChar     * ident,
                       SpiceBoolean  * found     )

#### Abstract

       Search through loaded SPK files to find the highest-priority segment
       applicable to the body and time specified.

#### Required_Reading

       SPK

#### Keywords

       EPHEMERIS
       FILES

#### Brief_I/O

       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       body       I   Body ID.
       et         I   Ephemeris time.
       idlen      I   Length of output segment ID string.
       handle     O   Handle of file containing the applicable segment.
       descr      O   Descriptor of the applicable segment.
       ident      O   Identifier of the applicable segment.
       found      O   Indicates whether or not a segment was found.
       SIDLEN     P   Maximum length of segment ID.

#### Detailed_Input

       body       is the NAIF integer code of an ephemeris object,
                  typically a solar system body.

       et         is a time, in seconds past the epoch J2000 TDB.

       idlen      is the allowed length of the output string.  This length
                  must large enough to hold the output segment ID plus the
                  null terminator. SPK segment identifiers may contain up
                  to SIDLEN characters, excluding the null terminator.

#### Detailed_Output

       handle     is the handle of the SPK file containing a located
                  segment.

       descr      is the descriptor of a located SPK segment. `descr'
                  has length 5.

       ident      is the SPK segment identifier of a located SPK segment.

       found      indicates whether a requested segment was found or not.
                  The other output arguments are valid only if `found'
                  is set to SPICETRUE.

#### Parameters

       SIDLEN     is the maximum number of characters in an SPK segment
                  identifier, excluding the null terminator.

                  SIDLEN is set to 40.

#### Exceptions

       1) If an attempt is made to call spksfs_c when there aren't any
          SPK files loaded, the error SPICE(NOLOADEDFILES) is signaled.

       2) With the exception of Fortran READ errors, any errors
          that occur while this routine attempts to extract segment
          descriptors from loaded SPK files will be diagnosed and signaled
          by routines in the call tree of this routine.

          Note however that I/O errors occurring during reads of DAF
          double precision records are NOT treated as SPICE errors
          and are not signaled.

#### Files

       All SPK files loaded by furnsh_c or spklef_c are potential search
       targets for spksfs_c.

#### Particulars

       This routine finds the highest-priority segment, in any loaded
       SPK file, such that the segment provides data for the specified
       body and epoch.

#### Examples

       1) Find a segment for the Pluto barycenter, with coverage for
          a specified epoch, in a JPL planetary SPK file.

          This example uses the following meta-kernel:

             KPL/MK

             This meta-kernel is intended to support operation of SPICE
             example programs. The kernels shown here should not be
             assumed to contain adequate or correct versions of data
             required by SPICE-based user applications.

             In order for an application to use this meta-kernel, the
             kernels referenced here must be present in the user's
             current working directory.

             The names and contents of the kernels referenced
             by this meta-kernel are as follows:

                File name                     Contents
                ---------                     --------
                de421.bsp                     Planetary ephemeris
                naif0010.tls                  Leapseconds

             \begindata

                KERNELS_TO_LOAD = ( 'de421.bsp'
                                    'naif0010.tls'  )

             \begintext

             End of meta-kernel

          Example code starts here.

             #include <stdio.h>
             #include "SpiceUsr.h"

             int main()
             {
                /.
                Local parameters
                ./
                #define ND                       2
                #define NI                       6
                #define DSCSIZ                   5
                #define SIDLEN1                 41

                /.
                Local variables
                ./
                SpiceBoolean            found;

                SpiceChar               segid   [ SIDLEN1 ];
                SpiceChar             * reqtim;

                SpiceDouble             dc      [ ND ];
                SpiceDouble             descr   [ DSCSIZ ];
                SpiceDouble             et;

                SpiceInt                handle;
                SpiceInt                ic      [ NI ];
                SpiceInt                idcode;

                /.
                Load a meta-kernel that specifies a planetary SPK file
                and leapseconds kernel. The contents of this meta-kernel
                are displayed above.
                ./
                furnsh_c ( "spksfs.tm" );

                /.
                Get the NAIF ID code for the Pluto system barycenter.
                This is a built-in ID code, so something's seriously
                wrong if we can't find the code.
                ./
                bodn2c_c ( "PLUTO BARYCENTER", &idcode, &found );

                if ( !found )
                {
                   sigerr_c( "SPICE(BUG)" );
                }

                /.
                Pick a request time; convert to seconds past J2000 TDB.
                ./
                reqtim = "2011 FEB 18 UTC";

                str2et_c ( reqtim, &et );

                /.
                Find a loaded segment for the specified body and time.
                ./
                spksfs_c ( idcode, et, SIDLEN1, &handle, descr, segid, &found );

                if ( !found )
                {
                   printf ( "No descriptor was found for ID %d at "
                            "TDB %24.17e\n",
                            (int) idcode,
                            et                                       );
                }
                else
                {
                   /.
                   Display the DAF file handle.
                   ./
                   printf ( "\n"
                            "DAF handle: %d\n"
                            "\n",
                            (int)handle        );

                   /.
                   Display the segment ID.

                   Unpack the descriptor. Display the contents.
                   ./
                   dafus_c ( descr, ND, NI, dc, ic );

                   printf ( "Segment found.\n"
                            "   Segment ID:        %s\n"
                            "   Body ID code:      %d\n"
                            "   Center ID code:    %d\n"
                            "   Frame ID code:     %d\n"
                            "   SPK data type:     %d\n"
                            "   Start time (TDB):  %24.17e\n"
                            "   Stop time  (TDB):  %24.17e\n",
                            segid,
                            (int) ic[0],
                            (int) ic[1],
                            (int) ic[2],
                            (int) ic[3],
                            dc[0],
                            dc[1]                             );
                }

                return ( 0 );
             }

          When executed on a PC/Linux/gcc platform, this program
          produced the following output:

             DAF handle: 1

             Segment found.
                Segment ID:        DE-0421LE-0421
                Body ID code:      9
                Center ID code:    0
                Frame ID code:     1
                SPK data type:     2
                Start time (TDB):  -3.16919520000000000e+09
                Stop time  (TDB):   1.69685280000000000e+09

#### Restrictions

       1) If a Fortran I/O error occurs while this routine searches a
          loaded SPK file, the internal state of SPK segment and file
          selection routines, which are all entry points in the f2c'd
          version for the Fortran routine SPKBSR, may be corrupted.

#### Literature_References

       SPK Required Reading.

#### Author_and_Institution

       N.J. Bachman    (JPL)
       R.E. Thurman    (JPL)

#### Version

       -CSPICE Version 1.0.1, 12-JUL-2016 (EDW)

          Edit to example program to use "%d" with explicit casts
          to int for printing SpiceInts with printf.

       -CSPICE Version 1.0.0, 05-OCT-2012 (NJB) (RET)

#### Index_Entries

       select spk file and segment

#### Link to routine spksfs_c source file spksfs_c.c

    Wed Apr  5 17:54:44 2017