spkw08_c |

Table of contents## Procedurespkw08_c ( Write SPK segment, type 8 ) void spkw08_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 8 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_Inputhandle 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 Lagrange 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. ## ParametersThe parameters below are declared in the Fortran include file spk08.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 8 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 ## 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 number of states `n' is not at least degree+1, the error SPICE(TOOFEWSTATES) is signaled by a routine in the call tree of this routine. 6) If `first' is greater than `last', the error SPICE(BADDESCRTIMES) is signaled by a routine in the call tree of this routine. 7) If `step' is non-positive, the error SPICE(INVALIDSTEPSIZE) is signaled by a routine in the call tree of this routine. 8) 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 above for a description of the tolerance. 9) If any of the `frame' or `segid' input string pointers is null, the error SPICE(NULLPOINTER) is signaled. 10) If any of the `frame' or `segid' input strings has zero length, the error SPICE(EMPTYSTRING) is signaled. ## FilesA new type 8 SPK segment is written to the SPK file attached to handle. ## ParticularsThis routine writes an SPK type 08 data segment to the open SPK file according to the format described in the type 08 section of the SPK Required Reading. The SPK file must have been opened with write access. ## ExamplesThe 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 8 kernel containing only one segment, given a time-ordered set of discrete states and epochs. Example code begins here. /. Program spkw08_ex1 ./ #include "SpiceUsr.h" int main( ) { /. Define the segment identifier parameters. ./ #define SPK8 "spkw08_ex1.bsp" #define REF "J2000" #define BODY 3 #define CENTER 10 #define DEGREE 3 #define NSTATS 9 /. Local variables. ./ SpiceChar * ifname; SpiceChar * segid; SpiceDouble begtim; SpiceDouble first; SpiceDouble last; SpiceDouble step; SpiceInt handle; SpiceInt ncomch; /. Set the array of discrete states to write to the SPK segment. ./ 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 separating epochs of states. ./ 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 8 SPK internal file name."; segid = "SPK type 8 test segment"; /. Open a new SPK file. ./ spkopn_c ( SPK8, ifname, ncomch, &handle ); /. Set the epoch of first state in `states' array to be the start time of the interval covered by the segment. ./ begtim = first; /. Create a type 8 segment. ./ ## 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) Edited the header to comply with NAIF standard. Added complete example code from existing fragment. Changed the input argument name "epoch1" to "begtim" for consistency with other routines. -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. -CSPICE Version 1.0.0, 29-JUN-1999 (NJB) ## Index_Entrieswrite SPK type_8 ephemeris data segment |

Fri Dec 31 18:41:13 2021