| spk14a_c |
|
Table of contents
Procedure
spk14a_c ( SPK, add data to a type 14 segment )
void spk14a_c ( SpiceInt handle,
SpiceInt ncsets,
ConstSpiceDouble coeffs [],
ConstSpiceDouble epochs [] )
AbstractAdd data to a type 14 SPK segment associated with `handle'. Required_ReadingSPK KeywordsSPK Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- handle I The handle of an SPK file open for writing. ncsets I The number of coefficient sets and epochs. coeffs I The collection of coefficient sets. epochs I The epochs associated with the coefficient sets. Detailed_Input
handle is the file handle of an SPK file that has been
opened for writing.
ncsets is the number of Chebyshev coefficient sets and epochs
to be stored in the segment.
coeffs is a time-ordered array of `ncsets' of Chebyshev polynomial
coefficients to be placed in the segment of the SPK file.
Each set has size SETSZ = 2 + 6*(CHBDEG+1), where CHBDEG
is the degree of the Chebyshev polynomials used to
represent the ephemeris information.
These sets are used to compute the state vector, which
consists of position components X, Y, Z and velocity
components dX/dt, dY/dt, dZ/dt, of a body relative to
a center of motion.
See the -Particulars section for details on how to store
the coefficient sets in the array.
epochs contains the initial epochs (ephemeris seconds past
J2000) corresponding to the Chebyshev coefficients in
`coeffs'. The I'th epoch is associated with the I'th
Chebyshev coefficient set. The epochs must form a
strictly increasing sequence.
Detailed_OutputNone. The ephemeris data is stored in a segment 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 number of coefficient sets and epochs is not positive,
the error SPICE(INVALIDARGUMENT) is signaled by a routine in
the call tree of this routine.
FilesNone. ParticularsThis routine adds data to a type 14 SPK segment that is associated with the input argument handle. The segment must have been started by a call to the routine spk14b_c, the routine which begins a type 14 SPK segment. 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 logical 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 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 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 spk14a_ex1
./
#include "SpiceUsr.h"
int main( )
{
/.
Define the segment identifier parameters.
./
#define SPK14 "spk14a_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.
2) This example demonstrates how to add type 14 SPK records to the
segment being written, one at a time. The ability to write the
records in this way is useful if computer memory is limited. It
may also be convenient from a programming perspective to write
the records this way.
Example code begins here.
/.
Program spk14a_ex2
./
#include "SpiceUsr.h"
int main( )
{
/.
Define the segment identifier parameters.
./
#define SPK14 "spk14a_ex2.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 i;
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 );
/.
Write the records to the segment in the
SPK file one at at time.
./
for ( i = 0; i < NRECS; i++ )
{
spk14a_c ( handle, 1, recrds[i], epochs+i );
}
/.
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 type 14 SPK segment to which we are adding data must have
been started by the routine SPK14B, the routine which begins a
type 14 SPK segment.
Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) K.R. Gehringer (JPL) Version
-CSPICE Version 1.0.1, 27-AUG-2021 (JDR) (NJB)
Updated header to comply with NAIF standard. Added complete examples
code from existing fragments.
Extended "coeffs" argument description to provide the size of the
Chebyshev polynomials sets.
Re-ordered header sections. Removed reference to other routines
from -Abstract section (already in -Particulars).
-CSPICE Version 1.0.0, 29-JUL-1999 (NJB) (KRG)
Index_Entriesadd data to a type_14 SPK segment |
Fri Dec 31 18:41:12 2021