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Index Page spkw12_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

       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        )

#### Abstract

       Write a type 12 segment to an SPK file.

#### Required_Reading

       NAIF_IDS
       SPC
       SPK
       TIME

#### Keywords

       EPHEMERIS
       FILES

#### Brief_I/O

       VARIABLE  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_Output

       None.

       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.

#### Files

       A new type 12 SPK segment is written to the SPK file attached
       to `handle'.

#### Particulars

       This 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.

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.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_Entries

       write SPK type_12 ephemeris data segment

#### Link to routine spkw12_c source file spkw12_c.c

    Fri Dec 31 18:41:13 2021