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spk14a_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

   void spk14a_c ( SpiceInt           handle,
                   SpiceInt           ncsets,
                   ConstSpiceDouble   coeffs [],
                   ConstSpiceDouble   epochs []  ) 

Abstract

 
   Add data to a type 14 SPK segment associated with handle. See 
   also spk14b_c and spk14e_c. 
 

Required_Reading

 
   SPK 
 

Keywords

 
   SPK 
 

Brief_I/O

 
   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   handle     I   The handle of an SPK file open for writing. 
   ncsets     I   The number of coefficient sets and epochs. 
   coeffs     I   The collection of coefficient sets. 
   epochs     I   The epochs associated with the coefficient sets. 
 

Detailed_Input

 
   handle   is the file handle of an SPK file that has been 
            opened for writing. 
 
   ncsets   is the number of Chebyshev coefficient sets and epochs 
            to be stored in the segment. 
 
   coeffs   contains a time-ordered array of Chebyshev coefficient 
            sets for computing the state vector of a body, packed one 
            after the other into an array.  A state vector contains 
            the position, X, Y, Z coordinates, and the velocities, 
            dX/dt, dY/dt, dZ/dt, for the position of a body relative 
            to a center of motion. 
 
            See the Particulars section for details on how to store 
            the coefficient sets in the array. 
 
   epochs   contains the initial epochs (ephemeris seconds past 
            J2000) corresponding to the Chebyshev coefficients in 
            COEFFS. The I'th epoch is associated with the I'th 
            Chebyshev coefficient set. The epochs must form a 
            strictly increasing sequence. 
 

Detailed_Output

 
   None.    The ephemeris data is stored in a segment in the SPK file 
            associated with handle. 
 
            See the Particulars section for details about the 
            structure of a type 14 SPK segment. 
 

Parameters

 
   None. 
 

Exceptions

 
   1) If the number of coefficient sets and epochs is not positive, 
      the error SPICE(INVALIDARGUMENT) will be signaled. 
 

Files

 
   None. 
 

Particulars

 
   This routine adds data to a type 14 SPK segment that is associated
   with the input argument handle. The segment must have been started
   by a call to the routine spk14b_c, the routine which begins a type
   14 SPK segment.
 
   This routine is one of a set of three routines for creating and 
   adding data to type 14 SPK segments. These routines are: 
 
      spk14b_c:  Begin a type 14 SPK segment. This routine must be 
                 called before any data may be added to a type 14 
                 segment. 
 
      spk14a_c:  Add data to a type 14 SPK segment. This routine may be 
                 called any number of times after a call to spk14b_c to 
                 add type 14 records to the SPK segment that was 
                 started. 
 
      spk14e_c:  End a type 14 SPK segment. This routine is called to 
                 make the type 14 segment a permanent addition to the 
                 SPK file. Once this routine is called, no further type 
                 14 records may be added to the segment. A new segment 
                 must be started. 
 
   A type 14 SPK segment consists of coefficient sets for fixed order 
   Chebyshev polynomials over consecutive time intervals, where the 
   time intervals need not all be of the same length. The Chebyshev 
   polynomials represent the position, X, Y, and Z coordinates, and 
   the velocities, dX/dt, dY/dt, and dZ/dt, of body relative to 
   center. 
 
   The ephemeris data supplied to the type 14 SPK writer is packed 
   into an array as a sequence of logical records, 
 
      ----------------------------------------------------- 
      | Record 1 | Record 2 | ... | Record N-1 | Record N | 
      ----------------------------------------------------- 
 
   with each record has the following format. 
 
         ------------------------------------------------ 
         |  The midpoint of the approximation interval  | 
         ------------------------------------------------ 
         |  The radius of the approximation interval    | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the X coordinate  | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the Y coordinate  | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the Z coordinate  | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the X velocity    | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the Y velocity    | 
         ------------------------------------------------ 
         |  CHBDEG+1 coefficients for the Z velocity    | 
         ------------------------------------------------ 
 
 

Examples

   Assume we have the following for each of the examples that 
   follow. 
 
      handle   is the handle of an SPK file opened with write 
               access. 
 
      segid    is a character string of no more than 40 characters 
               which provides a pedigree for the data in the SPK 
               segment we will create. 
 
      body     is the NAIF ID code for the body whose ephemeris 
               is to be placed into the file. 
 
      center   is the center of motion for the ephemeris of body. 
 
      reffrm   is the name of the SPICE reference frame for the 
               ephemeris. 
 
      first    is the starting epoch, in seconds past J2000, for 
               the ephemeris data to be placed into the segment. 
 
      last     is the ending epoch, in seconds past J2000, for 
               the ephemeris data to be placed into the segment. 
 
   Example 1: 
 
      For this example, we also assume that: 
 
         n        is the number of type 14 records that we want to 
                  put into a segment in an SPK file. 
 
         recrds   contains n type 14 records packaged for the SPK 
                  file. 
 
         etstrt   contains the initial epochs for each of the 
                  records contained in RECRDS, where 
 
                     etstrt[i] < etstrt[i+1], i = 0, n-2 
 
                     etstrt[1] <= first, etstrt[n-1] < last 
 
                     etstrt[i+1], i = 0, n-2, is the ending epoch for 
                     record i as well as the initial epoch for record 
                     i+1. 
 
      Then the following code fragment demonstrates how to create a 
      type 14 SPK segment if all of the data for the segment is 
      available at one time. 
 
         #include "SpiceUsr.h"
            .
            .
            .
         
         #define SPK  "example.bsp"
            
         /.
         If the segment is to be appended to an existing file, open
         that file for "append" access.  Otherwise, create a new file.
         ./
         
         if ( exists_c(SPK) )
         {
            spkopa_c ( SPK, &handle );
         } 
         else
         {
            /.
            New files are supplied with an internal file name.  
            Comment area space may be reserved at this time; the
            units are characters.
            ./
            ifname = "Sample type 14 SPK file.";
            ncomch = 1024;
            
            spkopn_c ( SPK, ifname, ncomch, &handle );
         }
          
          
         /.
         Begin the segment. 
         ./
         spk14b_c ( handle, segid, body, center, reffrm, 
                    first,  last,  chbdeg               );
       
         /.
         Add the data to the segment all at once. 
         ./
         spk14a_c ( handle, n, recrds, etstrt ); 
      
         /.
         End the segment, making the segment a permanent addition 
         to the SPK file. 
         ./
         spk14e_c ( handle ); 
         
             .
             .
             .
         /.
         After all segments have been loaded, close the SPK file.
         ./
         spkcls_c ( handle );
         
 
   Example 2: 
 
      In this example we want to add type 14 SPK records, as described
      above in the Particulars section, to the segments being written
      as they are generated.  The ability to write the records in this
      way is useful if computer memory is limited. It may also be
      convenient from a programming perspective to write the records
      one at a time.
 
      For this example, assume that we want to generate n type 14 SPK 
      records, one for each of n time intervals, writing them all to 
      the same segment in the SPK file. Let 
 
         n        be the number of type 14 records that we want to 
                  generate and put into a segment in an SPK file. 
 
         record   be an array with enough room to hold a single type 
                  14 record, i.e. record should have dimension at 
                  least 6 * (chbdeg + 1 ) + 2. 
 
         start    be an array of n times that are the beginning 
                  epochs for each of the intervals of interest. The 
                  times should be in increasing order and the start 
                  time for the first interval should equal the 
                  starting time for the segment. 
 
                     start[i] < start[i+1], i = 0, n-2 
 
                     start[0] = first 
 
         stop     be an array of n times that are the ending epochs 
                  for each of the intervals of interest. The times 
                  should be in increasing order and the stop time for 
                  interval i should equal the start time for interval 
                  i+1, i.e., we want to have continuous coverage in 
                  time across all of the records. Also, the stop time 
                  for the last interval should equal the ending time 
                  for the segment. 
 
                     stop[i]   < stop [i+1], i = 0, n-2 
 
                     stop[i]   = start[i+1], i = 0, n-2 
 
                     stop[n-1] = last 
 

         genrec( time1, time2, record ) 
 
                  be a subroutine that generates a type 14 SPK record 
                  for a time interval specified by time1 and time2. 
 

      Then the following code fragment demonstrates how to create a 
      type 14 SPK segment if all of the data for the segment is not 
      available at one time. 
 
         #include "SpiceUsr.h"
            .
            .
            .
        
         /.
         Begin the segment. 
         ./
         spk14b_c ( handle, segid, body, center, reffrm, 
                    first,  last,  chbdeg                ); 
 
        
         /.
         Generate the records and write them to the segment in the 
         SPK file one at at time. 
         ./   
         
         for ( i = 0;  i < n;  i++ )
         {
            genrec   ( start[i],     stop[i],  record   ); 
            spk14a_c ( handle,   1,  record,   start+i  );
         }
 
         /.
         End the segment, making the segment a permanent addition 
         to the SPK file. 
         ./   
         spk14e_c ( handle );
         
 
 

Restrictions

 
   1) The type 14 SPK segment to which we are adding data must have 
      been started by the routine SPK14B, the routine which begins a 
      type 14 SPK segment. 
 

Literature_References

 
   None. 
 

Author_and_Institution

 
   N.J. Bachman        (JPL)
   K.R. Gehringer      (JPL) 
 

Version

 
   -CSPICE Version 1.0.0, 29-JUL-1999 (NJB) (KRG)

Index_Entries

 
   add data to a type_14 spk segment 
 
Wed Apr  5 17:54:43 2017