| spkw12_c |
|
Table of contents
Procedure
spkw12_c ( Write SPK segment, type 12 )
void spkw12_c ( SpiceInt handle,
SpiceInt body,
SpiceInt center,
ConstSpiceChar * frame,
SpiceDouble first,
SpiceDouble last,
ConstSpiceChar * segid,
SpiceInt degree,
SpiceInt n,
ConstSpiceDouble states[][6],
SpiceDouble begtim,
SpiceDouble step )
AbstractWrite a type 12 segment to an SPK file. Required_ReadingNAIF_IDS SPC SPK TIME KeywordsEPHEMERIS FILES Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- MAXDEG P Maximum degree of interpolating polynomials. TOLSCL P Scale factor used to compute time bound tolerance. handle I Handle of an SPK file open for writing. body I NAIF code for an ephemeris object. center I NAIF code for center of motion of body. frame I Reference frame name. first I Start time of interval covered by segment. last I End time of interval covered by segment. segid I Segment identifier. degree I Degree of interpolating polynomials. n I Number of states. states I Array of states. begtim I Epoch of first state in states array. step I Time step separating epochs of states. MAXDEG P Maximum allowed degree of interpolating polynomial. Detailed_Input
handle is the file handle of an SPK file that has been
opened for writing.
body is the NAIF integer code for an ephemeris object
whose state relative to another body is described
by the segment to be created.
center is the NAIF integer code for the center of motion
of the object identified by body.
frame is the NAIF name for a reference frame
relative to which the state information for `body'
is specified.
first,
last are, respectively, the start and stop times of
the time interval over which the segment defines
the state of `body'.
segid is the segment identifier. An SPK segment
identifier may contain up to 40 characters.
degree is the degree of the Hermite polynomials used to
interpolate the states. All components of the
state vectors are interpolated by polynomials of
fixed degree.
n is the number of states in the input state vector
array.
states contains a time-ordered array of geometric states
( x, y, z, dx/dt, dy/dt, dz/dt, in kilometers and
kilometers per second ) of body relative to `center',
specified relative to `frame'.
begtim is the epoch corresponding to the first state in
the state array. Because extra states are needed
at the beginning and end of the segment in order
for the interpolation method to work, `begtim' will
normally precede first.
step is the time step separating the epochs of adjacent
states in the input state array. `step' is specified
in seconds.
Detailed_OutputNone. See -Particulars for a description of the effect of this routine. Parameters
The parameters below are declared in the Fortran include file
spk12.inc, which is part of the Fortran SPICE Toolkit (aka
SPICELIB). The values of those parameters are used in CSPICE code
generated by running f2c on SPICELIB source code. They are not
directly referenced by code in this module.
MAXDEG is the maximum allowed degree of the interpolating
polynomial.
The value of MAXDEG is 27.
TOLSCL is a tolerance scale factor (also called a
"relative tolerance") used for time coverage bound
checking. TOLSCL is unitless. TOLSCL produces a
tolerance value via the formula
TOL = TOLSCL * max( abs(first), abs(last) )
where `first' and `last' are the coverage time
bounds of a type 12 segment, expressed as seconds
past J2000 TDB.
The resulting parameter TOL is used as a tolerance
for comparing the input segment descriptor time
bounds to the first and last epoch covered by the
sequence of time intervals defined by the inputs
to spkw12_c:
begtim
step
n
The value of TOLSCL is 1.e-13.
Exceptions
If any of the following exceptions occur, this routine will return
without creating a new segment.
1) If `frame' is not a recognized name, the error
SPICE(INVALIDREFFRAME) is signaled by a routine in the call
tree of this routine.
2) If the last non-blank character of `segid' occurs past index 40,
the error SPICE(SEGIDTOOLONG) is signaled by a routine in the
call tree of this routine.
3) If `segid' contains any nonprintable characters, the error
SPICE(NONPRINTABLECHARS) is signaled by a routine in the call
tree of this routine.
4) If `degree' is not at least 1 or is greater than MAXDEG, the
error SPICE(INVALIDDEGREE) is signaled by a routine in the
call tree of this routine.
5) If `degree' is not odd, the error SPICE(INVALIDDEGREE) is
signaled by a routine in the call tree of this routine.
6) If the number of states `n' is not at least (degree+1)/2, the
error SPICE(TOOFEWSTATES) is signaled by a routine in the call
tree of this routine.
7) If `first' is greater than `last', the error SPICE(BADDESCRTIMES)
is signaled by a routine in the call tree of this routine.
8) If `step' is non-positive, the error SPICE(INVALIDSTEPSIZE) is
signaled by a routine in the call tree of this routine.
9) If the first epoch `begtim' is greater than `first', the error
SPICE(BADDESCRTIMES) is signaled by a routine in the call tree
of this routine.
10) If the start time of the first record exceeds the descriptor
begin time by more than a computed tolerance, or if the end
time of the last record precedes the descriptor end time by
more than a computed tolerance, the error SPICE(COVERAGEGAP)
is signaled by a routine in the call tree of this routine. See
the -Parameters section for a description of the tolerance.
11) If any of the `frame' or `segid' input string pointers is
null, the error SPICE(NULLPOINTER) is signaled.
12) If any of the `frame' or `segid' input strings has zero
length, the error SPICE(EMPTYSTRING) is signaled.
FilesA new type 12 SPK segment is written to the SPK file attached to `handle'. ParticularsThis routine writes an SPK type 12 data segment to the open SPK file according to the format described in the type 12 section of the SPK Required Reading. The SPK file must have been opened with write access. 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 12 kernel
containing only one segment, given an evenly-spaced
time-ordered set of discrete states.
Example code begins here.
/.
Program spkw12_ex1
./
#include "SpiceUsr.h"
int main( )
{
/.
Define the segment identifier parameters.
./
#define SPK12 "spkw12_ex1.bsp"
#define REF "J2000"
#define BODY 3
#define CENTER 10
#define DEGREE 3
#define NSTATS 9
/.
Local variables.
./
SpiceChar * ifname;
SpiceChar * segid;
SpiceDouble first;
SpiceDouble last;
SpiceDouble step;
SpiceInt handle;
SpiceInt ncomch;
/.
Define the states and epochs.
./
SpiceDouble states [NSTATS][6] = {
{101.0, 201.0, 301.0, 401.0, 501.0, 601.0},
{102.0, 202.0, 302.0, 402.0, 502.0, 602.0},
{103.0, 203.0, 303.0, 403.0, 503.0, 603.0},
{104.0, 204.0, 304.0, 404.0, 504.0, 604.0},
{105.0, 205.0, 305.0, 405.0, 505.0, 605.0},
{106.0, 206.0, 306.0, 406.0, 506.0, 606.0},
{107.0, 207.0, 307.0, 407.0, 507.0, 607.0},
{108.0, 208.0, 308.0, 408.0, 508.0, 608.0},
{109.0, 209.0, 309.0, 409.0, 509.0, 609.0} };
/.
Set the start and end times of interval covered by
segment, and the time step.
./
first = 100.0;
last = 900.0;
step = 100.0;
/.
`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 12 SPK internal file name.";
segid = "SPK type 12 test segment";
/.
Open a new SPK file.
./
spkopn_c ( SPK12, ifname, ncomch, &handle );
/.
Write the segment.
./
spkw12_c ( handle, BODY, CENTER, REF, first, last,
segid, DEGREE, NSTATS, states, first, step );
/.
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 12 exists in
the output directory.
RestrictionsNone. Literature_ReferencesNone. Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) Version
-CSPICE Version 2.1.0, 10-AUG-2021 (JDR)
Changed the input argument name "epoch1" to "begtim" for
consistency with other routines.
Edited the header to comply with NAIF standard. Added
complete example code from existing fragment.
-CSPICE Version 2.0.0, 11-JAN-2014 (NJB)
Relaxed test on relationship between the time bounds of the
input record set (determined by `begtim', `step', and `n') and
the descriptor bounds `first' and `last'. Now the descriptor
bounds may extend beyond the time bounds of the record set by a
ratio computed using the parameter TOLSCL (see -Parameters above
for details). Added checks on input polynomial degree.
Renamed argument `epoch0' to `epoch1' for consistency with other
CSPICE and SPICELIB interfaces.
-CSPICE Version 1.0.0, 23-FEB-2000 (NJB)
Index_Entrieswrite SPK type_12 ephemeris data segment |
Fri Dec 31 18:41:13 2021