| spkcov_c |
|
Table of contents
Procedure
spkcov_c ( SPK coverage )
void spkcov_c ( ConstSpiceChar * spkfnm,
SpiceInt idcode,
SpiceCell * cover )
AbstractFind the coverage window for a specified ephemeris object in a specified SPK file. Required_ReadingCELLS DAF SPK TIME WINDOWS KeywordsEPHEMERIS TIME UTILITY Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- spkfnm I Name of SPK file. idcode I ID code of ephemeris object. cover I-O Window giving coverage in `spkfnm' for `idcode'. Detailed_Input
spkfnm is the name of an SPK file.
idcode is the integer ID code of an object for which ephemeris
data are expected to exist in the specified SPK file.
cover is an initialized SPICE window data structure. `cover'
optionally may contain coverage data on input; on output,
the data already present in `cover' will be combined with
coverage found for the object designated by `idcode' in the
file `spkfnm'.
If `cover' contains no data on input, its size and
cardinality still must be initialized.
`cover' must be declared as a double precision SpiceCell.
CSPICE provides the following macro, which declares and
initializes the cell
SPICEDOUBLE_CELL ( cover, COVERSZ );
where COVERSZ is the maximum capacity of `cover'.
Detailed_Output
cover is a SPICE window data structure which represents the
merged coverage for `idcode'. This is the set of time
intervals for which data for `idcode' are present in the
file `spkfnm', merged with the set of time intervals
present in `cover' on input. The merged coverage is
represented as the union of one or more disjoint time
intervals. The window `cover' contains the pairs of
endpoints of these intervals.
The interval endpoints contained in `cover' are ephemeris
times, expressed as seconds past J2000 TDB.
See the -Examples section below for a complete example
program showing how to retrieve the endpoints from `cover'.
ParametersNone. Exceptions
1) If the input file has transfer format, the error
SPICE(INVALIDFORMAT) is signaled by a routine in the call tree
of this routine.
2) If the input file is not a transfer file but has architecture
other than DAF, the error SPICE(INVALIDARCHTYPE) is signaled
by a routine in the call tree of this routine.
3) If the input file is a binary DAF file of type other than SPK,
the error SPICE(INVALIDFILETYPE) is signaled by a routine in
the call tree of this routine.
4) If the SPK file cannot be opened or read, an error is signaled
by a routine in the call tree of this routine. The output
window will not be modified.
5) If the size of the output window argument `cover' is
insufficient to contain the actual number of intervals in the
coverage window for `idcode', an error is signaled by a routine
in the call tree of this routine.
6) If the `spkfnm' input string pointer is null, the error
SPICE(NULLPOINTER) is signaled.
7) If the `spkfnm' input string has zero length, the error
SPICE(EMPTYSTRING) is signaled.
8) If the `cover' cell argument has a type other than
SpiceDouble, the error SPICE(TYPEMISMATCH) is signaled.
FilesThis routine reads an SPK file. ParticularsThis routine provides an API via which applications can determine the coverage a specified SPK file provides for a specified ephemeris object. Examples
The numerical results shown for these examples may differ across
platforms. The results depend on the SPICE kernels used as
input, the compiler and supporting libraries, and the machine
specific arithmetic implementation.
1) This example demonstrates combined usage of spkcov_c and the
related SPK utility spkobj_c.
Display the coverage for each object in a specified SPK file.
Find the set of objects in the file; for each object, find
and display the coverage.
Example code begins here.
/.
Program spkcov_ex1
./
#include <stdio.h>
#include "SpiceUsr.h"
int main()
{
/.
Local parameters
./
#define FILSIZ 256
#define MAXIV 1000
#define WINSIZ ( 2 * MAXIV )
#define TIMLEN 51
#define MAXOBJ 1000
/.
Local variables
./
SPICEDOUBLE_CELL ( cover, WINSIZ );
SPICEINT_CELL ( ids, MAXOBJ );
SpiceChar lsk [ FILSIZ ];
SpiceChar spkfnm [ FILSIZ ];
SpiceChar timstr [ TIMLEN ];
SpiceDouble b;
SpiceDouble e;
SpiceInt i;
SpiceInt j;
SpiceInt niv;
SpiceInt obj;
/.
Load a leapseconds kernel for output time conversion.
spkcov_c itself does not require a leapseconds kernel.
./
prompt_c ( "Name of leapseconds kernel > ", FILSIZ, lsk );
furnsh_c ( lsk );
/.
Get name of SPK file.
./
prompt_c ( "Name of SPK file > ", FILSIZ, spkfnm );
/.
Find the set of objects in the SPK file.
./
spkobj_c ( spkfnm, &ids );
/.
We want to display the coverage for each object. Loop over
the contents of the ID code set, find the coverage for
each item in the set, and display the coverage.
./
for ( i = 0; i < card_c( &ids ); i++ )
{
/.
Find the coverage window for the current object.
Empty the coverage window each time so we don't
include data for the previous object.
./
obj = SPICE_CELL_ELEM_I( &ids, i );
scard_c ( 0, &cover );
spkcov_c ( spkfnm, obj, &cover );
/.
Get the number of intervals in the coverage window.
./
niv = wncard_c ( &cover );
/.
Display a simple banner.
./
printf ( "%s\n", "========================================" );
printf ( "Coverage for object %d\n", (int)obj );
/.
Convert the coverage interval start and stop times to TDB
calendar strings.
./
for ( j = 0; j < niv; j++ )
{
/.
Get the endpoints of the jth interval.
./
wnfetd_c ( &cover, j, &b, &e );
/.
Convert the endpoints to TDB calendar
format time strings and display them.
./
timout_c ( b,
"YYYY MON DD HR:MN:SC.### (TDB) ::TDB",
TIMLEN,
timstr );
printf ( "\n"
"Interval: %d\n"
"Start: %s\n",
(int)j,
timstr );
timout_c ( e,
"YYYY MON DD HR:MN:SC.### (TDB) ::TDB",
TIMLEN,
timstr );
printf ( "Stop: %s\n", timstr );
}
}
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, using the LSK file named naif0012.tls and the SPK
file named mar097.bsp, the output was:
Name of leapseconds kernel > naif0012.tls
Name of SPK file > mar097.bsp
========================================
Coverage for object 3
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 4
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 10
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 399
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 401
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 402
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
========================================
Coverage for object 499
Interval: 0
Start: 1900 JAN 04 00:00:41.184 (TDB)
Stop: 2100 JAN 01 00:01:07.183 (TDB)
2) Find the coverage for the object designated by `idcode'
provided by the set of SPK files loaded via a metakernel.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File: spkcov_ex2.tm
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
--------- --------
de430.bsp Planetary ephemeris
mar097.bsp Mars satellite ephemeris
naif0011.tls Leapseconds
\begindata
KERNELS_TO_LOAD = ( 'de430.bsp',
'mar097.bsp',
'naif0011.tls' )
\begintext
End of meta-kernel
Example code begins here.
/.
Program spkcov_ex2
./
#include <stdio.h>
#include "SpiceUsr.h"
int main()
{
/.
Local parameters
./
#define FILSIZ 256
#define LNSIZE 81
#define MAXCOV 100000
#define WINSIZ ( 2 * MAXCOV )
#define TIMLEN 51
/.
Local variables
./
SPICEDOUBLE_CELL ( cover, WINSIZ );
SpiceBoolean found;
SpiceChar file [ FILSIZ ];
SpiceChar idch [ LNSIZE ];
SpiceChar meta [ FILSIZ ];
SpiceChar source [ FILSIZ ];
SpiceChar timstr [ TIMLEN ];
SpiceChar type [ LNSIZE ];
SpiceDouble b;
SpiceDouble e;
SpiceInt count;
SpiceInt handle;
SpiceInt i;
SpiceInt idcode;
SpiceInt niv;
/.
Prompt for the metakernel name; load the metakernel.
The metakernel lists the SPK files whose coverage
for `idcode' we'd like to determine. The metakernel
must also specify a leapseconds kernel.
./
prompt_c ( "Name of metakernel > ", FILSIZ, meta );
furnsh_c ( meta );
/.
Get the ID code of interest.
./
prompt_c ( "Enter ID code > ", LNSIZE, idch );
prsint_c ( idch, &idcode );
/.
Find out how many kernels are loaded. Loop over the
kernels: for each loaded SPK file, add its coverage
for `idcode', if any, to the coverage window.
./
ktotal_c ( "SPK", &count );
for ( i = 0; i < count; i++ )
{
kdata_c ( i, "SPK", FILSIZ, LNSIZE, FILSIZ,
file, type, source, &handle, &found );
spkcov_c ( file, idcode, &cover );
}
/.
Display results.
Get the number of intervals in the coverage window.
./
niv = wncard_c ( &cover );
/.
Display a simple banner.
./
printf ( "\nCoverage for object %d\n", (int)idcode );
/.
Convert the coverage interval start and stop times to TDB
calendar strings.
./
for ( i = 0; i < niv; i++ )
{
/.
Get the endpoints of the ith interval.
./
wnfetd_c ( &cover, i, &b, &e );
/.
Convert the endpoints to TDB calendar
format time strings and display them.
./
timout_c ( b,
"YYYY MON DD HR:MN:SC.### (TDB) ::TDB",
TIMLEN,
timstr );
printf ( "\n"
"Interval: %d\n"
"Start: %s\n",
(int)i,
timstr );
timout_c ( e,
"YYYY MON DD HR:MN:SC.### (TDB) ::TDB",
TIMLEN,
timstr );
printf ( "Stop: %s\n", timstr );
}
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, using the meta-kernel named spkcov_ex2.tm provided
above to find the coverage window for the Earth using its ID
code, "399", the output was:
Name of metakernel > spkcov_ex2.tm
Enter ID code > 399
Coverage for object 399
Interval: 0
Start: 1549 DEC 31 00:00:00.000 (TDB)
Stop: 2650 JAN 25 00:00:00.000 (TDB)
Restrictions
1) If an error occurs while this routine is updating the window
`cover', the window may be corrupted.
Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) E.D. Wright (JPL) Version
-CSPICE Version 1.1.0, 25-AUG-2021 (JDR)
Changed input argument name "spk" to "spkfnm" for consistency with other
routines.
Edited the header to comply with NAIF standard. Added examples' solution
and meta-kernel for example #2. Corrected short error message in entries
#2 and #3 in -Exceptions section and added entry #8.
Extended description of argument "cover" in -Detailed_Input to include
type and preferred declaration method.
-CSPICE Version 1.0.3, 14-JUN-2016 (EDW)
Edit to example program to use "%d" with explicit casts
to int for printing SpiceInts with printf.
-CSPICE Version 1.0.2, 01-JUL-2014 (NJB)
Added new index entries.
-CSPICE Version 1.0.1, 30-NOV-2007 (NJB)
Corrected bug in first example program in header:
program now empties result window prior to collecting
data for each object. Deleted declaration of unused
constant NAMLEN. Updated examples to use wncard_c
rather than card_c.
-CSPICE Version 1.0.0, 30-DEC-2004 (NJB)
Index_Entriesget coverage window for spk_object get coverage start and stop time for spk_object get coverage start and stop time for ephemeris_object get coverage start and stop time for body |
Fri Dec 31 18:41:12 2021