spkw18_c |

Table of contents## Procedurespkw18_c ( Write SPK segment, type 18 ) void spkw18_c ( SpiceInt handle, SpiceSPK18Subtype subtyp, SpiceInt body, SpiceInt center, ConstSpiceChar * frame, SpiceDouble first, SpiceDouble last, ConstSpiceChar * segid, SpiceInt degree, SpiceInt n, const void * packts, ConstSpiceDouble epochs[] ) ## AbstractWrite a type 18 segment to an SPK file. ## Required_ReadingNAIF_IDS SPC SPK TIME ## KeywordsEPHEMERIS FILES ## Brief_I/OVARIABLE 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 packets. packts I Array of packets. epochs I Array of epochs corresponding to packets. MAXDEG P Maximum allowed degree of interpolating polynomial. ## Detailed_Inputhandle is the file handle of an SPK file that has been opened for writing. subtyp is an integer code indicating the subtype of 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. If the actual interpolation degree is reduced, the highest degree feasible degree valid for the interpolation type is used. n is the number of packets in the input packet array. packts is 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. ## Detailed_OutputNone. See -Particulars for a description of the effect of this routine. ## ParametersMAXDEG is the maximum allowed degree of the interpolating polynomial. Its current value is 15. ## ExceptionsIf 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 the window size implied by `degree' is odd, the error SPICE(INVALIDDEGREE) is signaled by a routine in the call tree of this routine. 6) If the number of packets `n' is not at least 2, the error SPICE(TOOFEWSTATES) is signaled by a routine in the call tree of this routine. 7) If `first' is greater than or equal to `last', the error SPICE(BADDESCRTIMES) is signaled by a routine in the call tree of this routine. 8) If the elements of the array `epochs' are not in strictly increasing order, the error SPICE(TIMESOUTOFORDER) is signaled by a routine in the call tree of this routine. 9) If the first epoch epochs[0] is greater than `first', the error SPICE(BADDESCRTIMES) is signaled by a routine in the call tree of this routine. 10) If the last epoch epochs[n-1] is less than `last', the error SPICE(BADDESCRTIMES) is signaled by a routine in the call tree of this routine. 11) If the subtype code is not recognized, the error SPICE(INVALIDVALUE) is signaled by a routine in the call tree of this routine. 12) If any of the `frame' or `segid' input string pointers is null, the error SPICE(NULLPOINTER) is signaled. 13) If any of the `frame' or `segid' input strings has zero length, the error SPICE(EMPTYSTRING) is signaled. ## FilesA new type 18 SPK segment is written to the SPK file attached to `handle'. ## ParticularsThis 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. ## ExamplesSuppose 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. ./ ## RestrictionsNone. ## Literature_ReferencesNone. ## Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) ## Version-CSPICE Version 1.0.2, 13-AUG-2021 (JDR) Edited the header to comply with NAIF standard. Changed, in the documentation, the argument name "state" to "packts". Fixed exception entry #6, since the number of packets must be at least 2 and not 1. Added exception entry #11. Updated -Parameters section to remove reference to SPICELIB routines and add the actual value of the MAXDEG parameter. -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) ## Index_Entrieswrite SPK type_18 ephemeris data segment |

Fri Dec 31 18:41:13 2021