| spk14b_c |
|
Table of contents
Procedure
spk14b_c ( SPK, begin a type 14 segment )
void spk14b_c ( SpiceInt handle,
ConstSpiceChar * segid,
SpiceInt body,
SpiceInt center,
ConstSpiceChar * frame,
SpiceDouble first,
SpiceDouble last,
SpiceInt chbdeg )
AbstractBegin a type 14 SPK segment in the SPK file associated with `handle'. Required_ReadingSPK KeywordsSPK Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- handle I The handle of an SPK file open for writing. segid I The string to use for segment identifier. body I The NAIF ID code for the body of the segment. center I The center of motion for body. frame I The reference frame for this segment. first I The first epoch for which the segment is valid. last I The last epoch for which the segment is valid. chbdeg I The degree of the Chebyshev Polynomial used. Detailed_Input
handle is the file handle of an SPK file that has been
opened for writing.
segid is the segment identifier. An SPK segment identifier
may contain up to 40 printing ASCII characters.
body is the NAIF ID for the body whose states are
to be recorded in an SPK file.
center is the NAIF ID for the center of motion associated
with body.
frame is the reference frame that states are referenced to,
for example "J2000".
first is the starting epoch, in TDB seconds past J2000, for
the ephemeris data to be placed into the segment.
last is the ending epoch, in TDB seconds past J2000, for
the ephemeris data to be placed into the segment.
chbdeg is the degree of the Chebyshev Polynomials used to
represent the ephemeris information stored in the
segment.
Detailed_OutputNone. The input data is used to create the segment summary for the segment being started in the SPK file associated with `handle'. See the -Particulars section for details about the structure of a type 14 SPK segment. ParametersNone. Exceptions
1) If the degree of the Chebyshev Polynomial to be used for this
segment is negative, the error SPICE(INVALIDARGUMENT) is
signaled by a routine in the call tree of this routine.
2) If there are issues in the structure or content of the inputs
other than the degree of the Chebyshev Polynomial, an error is
signaled by a routine in the call tree of this routine.
3) If a file access error occurs, the error is signaled by a
routine in the call tree of this routine.
4) If any of the `frame' or `segid' input string pointers is
null, the error SPICE(NULLPOINTER) is signaled.
5) If any of the `frame' or `segid' input strings has zero
length, the error SPICE(EMPTYSTRING) is signaled.
FilesSee handle in the -Detailed_Input section. Particulars
This routine begins writing a type 14 SPK segment to the open SPK
file that is associated with `handle'. The file must have been
opened with write access.
This routine is one of a set of three routines for creating and
adding data to type 14 SPK segments. These routines are:
spk14b_c: Begin a type 14 SPK segment. This routine must be
called before any data may be added to a type 14
segment.
spk14a_c: Add data to a type 14 SPK segment. This routine may be
called any number of times after a call to spk14b_c to
add type 14 records to the SPK segment that was
started.
spk14e_c: End a type 14 SPK segment. This routine is called to
make the type 14 segment a permanent addition to the
SPK file. Once this routine is called, no further type
14 records may be added to the segment. A new segment
must be started.
A type 14 SPK segment consists of coefficient sets for fixed order
Chebyshev polynomials over consecutive time intervals, where the
time intervals need not all be of the same length. The Chebyshev
polynomials represent the position, X, Y, and Z coordinates, and
the velocities, dX/dt, dY/dt, and dZ/dt, of body relative to
center.
The ephemeris data supplied to the type 14 SPK writer is packed
into an array as a sequence of records,
-----------------------------------------------------
| Record 1 | Record 2 | ... | Record N-1 | Record N |
-----------------------------------------------------
with each record has the following format.
------------------------------------------------
| The midpoint of the approximation interval |
------------------------------------------------
| The radius of the approximation interval |
------------------------------------------------
| chbdeg+1 coefficients for the X coordinate |
------------------------------------------------
| chbdeg+1 coefficients for the Y coordinate |
------------------------------------------------
| chbdeg+1 coefficients for the Z coordinate |
------------------------------------------------
| chbdeg+1 coefficients for the X velocity |
------------------------------------------------
| chbdeg+1 coefficients for the Y velocity |
------------------------------------------------
| chbdeg+1 coefficients for the Z velocity |
------------------------------------------------
Examples
The numerical results shown for this example 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 how to create an SPK type 14 kernel
containing only one segment, given a set of Chebyshev
coefficients and their associated epochs.
Example code begins here.
/.
Program spk14b_ex1
./
#include "SpiceUsr.h"
int main( )
{
/.
Define the segment identifier parameters.
./
#define SPK14 "spk14b_ex1.bsp"
#define REF "J2000"
#define BODY 3
#define CENTER 10
#define CHBDEG 2
#define NRECS 4
#define RECSIZ ( 2 + 6*(CHBDEG+1) )
/.
Local variables.
./
SpiceChar * ifname;
SpiceChar * segid;
SpiceDouble first;
SpiceDouble last;
SpiceInt handle;
SpiceInt ncomch;
/.
Define the epochs and coefficients.
./
SpiceDouble epochs [NRECS+1] = {
100.0, 200.0, 300.0, 400.0, 500.0 };
SpiceDouble recrds [NRECS][RECSIZ] = {
{150.0, 50.0,
1.0101, 1.0102, 1.0103,
1.0201, 1.0202, 1.0203,
1.0301, 1.0302, 1.0303,
1.0401, 1.0402, 1.0403,
1.0501, 1.0502, 1.0503,
1.0601, 1.0602, 1.0603},
{250.0, 50.0,
2.0101, 2.0102, 2.0103,
2.0201, 2.0202, 2.0203,
2.0301, 2.0302, 2.0303,
2.0401, 2.0402, 2.0403,
2.0501, 2.0502, 2.0503,
2.0601, 2.0602, 2.0603},
{350.0, 50.0,
3.0101, 3.0102, 3.0103,
3.0201, 3.0202, 3.0203,
3.0301, 3.0302, 3.0303,
3.0401, 3.0402, 3.0403,
3.0501, 3.0502, 3.0503,
3.0601, 3.0602, 3.0603},
{450.0, 50.0,
4.0101, 4.0102, 4.0103,
4.0201, 4.0202, 4.0203,
4.0301, 4.0302, 4.0303,
4.0401, 4.0402, 4.0403,
4.0501, 4.0502, 4.0503,
4.0601, 4.0602, 4.0603} };
/.
Set the start and end times of interval covered by
segment.
./
first = epochs[0];
last = epochs[NRECS];
/.
`ncomch' is the number of characters to reserve for the
kernel's comment area. This example doesn't write
comments, so set to zero.
./
ncomch = 0;
/.
Internal file name and segment ID.
./
ifname = "Type 14 SPK internal file name.";
segid = "SPK type 14 test segment";
/.
Open a new SPK file.
./
spkopn_c ( SPK14, ifname, ncomch, &handle );
/.
Begin the segment.
./
spk14b_c ( handle, segid, BODY, CENTER, REF, first, last, CHBDEG );
/.
Add the data to the segment all at once.
./
spk14a_c ( handle, NRECS, recrds, epochs );
/.
End the segment, making the segment a permanent addition
to the SPK file.
./
spk14e_c ( handle );
/.
Close the SPK file.
./
spkcls_c ( handle );
return ( 0 );
}
When this program is executed, no output is presented on
screen. After run completion, a new SPK type 14 exists in
the output directory.
Restrictions
1) The SPK file must be open with write access.
2) Only one segment may be written to a particular SPK file at a
time. All of the data for the segment must be written and the
segment must be ended before another segment may be started in
the file.
Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) K.R. Gehringer (JPL) B.V. Semenov (JPL) Version
-CSPICE Version 1.0.2, 27-AUG-2021 (JDR)
Edited the header to comply with NAIF standard. Added
complete example code from existing fragment.
Removed reference to other routines from -Abstract section
(already in -Particulars).
-CSPICE Version 1.0.1, 30-OCT-2006 (BVS)
Deleted "inertial" from the "frame" description in the -Brief_I/O
section of the header.
-CSPICE Version 1.0.0, 29-JUL-1999 (NJB) (KRG)
Index_Entriesbegin writing a type_14 SPK segment |
Fri Dec 31 18:41:12 2021