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Index Page spkw18_c

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Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       spkw18_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[]     )

#### Abstract

       Write a type 18 segment to an SPK file.

#### Required_Reading

       NAIF_IDS
       SPC
       SPK
       TIME

#### Keywords

       EPHEMERIS
       FILES

#### Brief_I/O

       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 packets.
       packts     I   Array of packets.
       epochs     I   Array of epochs corresponding to packets.
       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.

       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_Output

       None. See -Particulars for a description of the effect of this
       routine.

#### Parameters

       MAXDEG      is the maximum allowed degree of the interpolating polynomial.
                   Its current value is 15.

#### 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 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.

#### Files

       A new type 18 SPK segment is written to the SPK file attached
       to `handle'.

#### Particulars

       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.

#### Examples

       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 );

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.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_Entries

       write SPK type_18 ephemeris data segment

#### Link to routine spkw18_c source file spkw18_c.c

    Fri Dec 31 18:41:13 2021