Write a type 18 segment to an SPK file.
NAIF_IDS SPC SPK TIME
Variable I/O Description -------- --- -------------------------------------------------- handle I Handle of an SPK file open for writing. subtyp I SPK type 18 subtype code. 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. epochs I Array of epochs corresponding to states. MAXDEG P Maximum allowed degree of interpolating polynomial.
handle is the file handle of an SPK file that has been opened for writing. subtyp is an integer code indicating the subtype of the the segment to be created. 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 nominal degree of the polynomials used to interpolate the states contained in the input packets. All components of the state vectors are interpolated by polynomials of the specified degree, except near the segment boundaries, or if the total number of states in the segment is too few to allow interpolation using the specified degree. n is the number of packets in the input packet array. packts contains a time-ordered array of data packets representing geometric states of body relative to center, specified relative to frame. The packet structure depends on the segment subtype as follows: Type 0 (indicated by code S18TP0): x, y, z, dx/dt, dy/dt, dz/dt, vx, vy, vz, dvx/dt, dvy/dt, dvz/dt where x, y, z represent Cartesian position components and vx, vy, vz represent Cartesian velocity components. Note well: vx, vy, and vz *are not necessarily equal* to the time derivatives of x, y, and z. This packet structure mimics that of the Rosetta/MEX orbit file from which the data are taken. Type 1 (indicated by code S18TP1): x, y, z, dx/dt, dy/dt, dz/dt where x, y, z represent Cartesian position components and vx, vy, vz represent Cartesian velocity components. Position units are kilometers, velocity units are kilometers per second, and acceleration units are kilometers per second per second. epochs is an array of epochs corresponding to the members of the packets array. The epochs are specified as seconds past J2000, TDB.
None. See $Particulars for a description of the effect of this routine.
MAXDEG is the maximum allowed degree of the interpolating polynomial. If the value of MAXDEG is increased, the CSPICE routine spkpvn_ must be changed accordingly. In particular, the size of the record passed to SPKRnn and SPKEnn must be increased, and comments describing the record size must be changed.
This routine writes an SPK type 18 data segment to the open SPK file according to the format described in the type 18 section of the SPK Required Reading. The SPK file must have been opened with write access.
Suppose that you have states and are prepared to produce a segment of type 18 in an SPK file. The following code fragment could be used to add the new segment to a previously opened SPK file attached to handle. The file must have been opened with write access. #include "SpiceUsr.h" . . . /. Create a segment identifier. ./ #define SEGID "MY_SAMPLE_SPK_TYPE_18_SEGMENT" /. Write the segment. ./ spkw18_c ( handle, subtyp, body, center, frame, first, last, segid, degree, n, states, epochs );
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. 2) If the last non-blank character of segid occurs past index 40, the error SPICE(SEGIDTOOLONG) is signaled. 3) If segid contains any nonprintable characters, the error SPICE(NONPRINTABLECHARS) is signaled. 4) If degree is not at least 1 or is greater than MAXDEG, the error SPICE(INVALIDDEGREE) is signaled. 5) If the window size implied by DEGREE is odd, the error SPICE(INVALIDDEGREE) is signaled. 6) If the number of packets n is not at least 1, the error SPICE(TOOFEWSTATES) will be signaled. 7) If first is greater than or equal to last then the error SPICE(BADDESCRTIMES) will be signaled. 8) If the elements of the array epochs are not in strictly increasing order, the error SPICE(TIMESOUTOFORDER) will be signaled. 9) If the first epoch epochs is greater than first, the error SPICE(BADDESCRTIMES) will be signaled. 10) If the last epoch epochs[n-1] is less than last, the error SPICE(BADDESCRTIMES) will be signaled. 11) If either the input frame or segment ID string pointer is null, the error SPICE(NULLPOINTER) is signaled. 12) If either the input frame or segment ID string is empty, the error SPICE(EMPTYSTRING) is signaled.
A new type 18 SPK segment is written to the SPK file attached to HANDLE.
N.J. Bachman (JPL)
-CSPICE Version 1.0.1, 29-APR-2003 (NJB) Description of error condition arising from invalid window size was corrected. -CSPICE Version 1.0.0, 16-AUG-2002 (NJB)
write spk type_18 ephemeris data segment