Index of Functions: A B C D E F G H I J K L M N O P Q R S T U V W X
Index Page cknr03_c

Table of contents

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

       cknr03_c ( C-kernel, number of records, type 03 )

       void cknr03_c ( SpiceInt            handle,
                       ConstSpiceDouble    descr  [],
                       SpiceInt          * nrec      )

#### Abstract

       Return the number of pointing instances in a CK type 03 segment.
       The segment is identified by a CK file handle and segment
       descriptor.

#### Required_Reading

       CK
       DAF

#### Keywords

       POINTING

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       handle     I   The handle of the CK file containing the segment.
       descr      I   The descriptor of the type 3 segment.
       nrec       O   The number of pointing instances in the segment.

#### Detailed_Input

       handle      is the handle of the binary CK file containing the
                   segment. The file should have been opened for read
                   or write access, by cklpf_c, dafopr_c or dafopw_c.

       descr       is the packed descriptor of a data type 3 CK segment.

#### Detailed_Output

       nrec        is the number of pointing instances in the type 3
                   segment.

#### Parameters

       None.

#### Exceptions

       1)  If the segment indicated by `descr' is not a type 3 segment, the
           error SPICE(CKWRONGDATATYPE) is signaled by a routine in the call
           tree of this routine.

       2)  If the specified handle does not belong to any DAF file that
           is currently known to be open, an error is signaled by a
           routine in the call tree of this routine.

       3)  If `descr' is not a valid descriptor of a segment in the CK
           file specified by `handle', the results of this routine are
           unpredictable.

#### Files

       The CK file specified by `handle' should be open for read or
       write access.

#### Particulars

       For a complete description of the internal structure of a type 3
       segment, see the CK required reading.

       This routine returns the number of discrete pointing instances
       contained in the specified segment. It is normally used in
       conjunction with ckgr03_c which returns the Ith pointing instance
       in the segment.

#### 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) The following code example extracts the SCLK time, boresight
          vector, and angular velocity vector for each pointing instance
          in the first segment in a CK file that contains segments of
          data type 3.

          Use the CK kernel below, available in the Venus Express PDS
          archives, as input for the code example.

             VEX_BOOM_V01.BC

          Example code begins here.

          /.
             Program cknr03_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local variables.
             ./
             SpiceDouble          quat   [4];
             SpiceDouble          av     [3];
             SpiceDouble          bore   [3];
             SpiceDouble          cmat   [3][3];
             SpiceDouble          dcd    [2];
             SpiceDouble          descr  [5];
             SpiceDouble          record [8];
             SpiceDouble          sclkdp;

             SpiceInt             i;
             SpiceInt             icd    [6];
             SpiceInt             handle;
             SpiceInt             nrec;

             SpiceBoolean         avseg;
             SpiceBoolean         found;

             /.
             First load the file (it may also be opened by
             using cklpf_c).
             ./
             dafopr_c ( "VEX_BOOM_V01.BC", &handle );

             /.
             Begin forward search.  Find the first array.
             ./
             dafbfs_c ( handle );
             daffna_c ( &found );

             /.
             Get segment descriptor.
             ./
             dafgs_c ( descr );

             /.
             Unpack the segment descriptor into its double precision
             and integer components.
             ./
             dafus_c ( descr, 2, 6, dcd, icd );

             /.
             The data type for a segment is located in the third
             integer component of the descriptor.
             ./
             if ( icd[2] == 3 )
             {

                /.
                Does the segment contain `av' data?
                ./
                avseg =  ( icd[3] == 1 );

                /.
                How many records does this segment contain?
                ./
                cknr03_c ( handle, descr, &nrec );

                for ( i = 1; i <= nrec; i++ )
                {

                   /.
                   Get the ith pointing instance in the segment.
                   ./
                   ckgr03_c ( handle, descr, i, record );

                   /.
                   Unpack `record' into the time, quaternion, and av.
                   ./
                   sclkdp = record[0];

                   moved_c ( record+1, 4, quat );

                   if ( avseg )
                   {
                      moved_c ( record+5, 3, av );
                   }

                   /.
                   The boresight vector is the third row of the
                   C-matrix.
                   ./
                   q2m_c ( quat, cmat );

                   bore[0] = cmat[2][0];
                   bore[1] = cmat[2][1];
                   bore[2] = cmat[2][2];

                   /.
                   Write out the results.
                   ./
                   printf( "Record: %2d\n", (int)i );
                   printf( "   SCLK time       : %24.6f\n", sclkdp );
                   printf( "   Boresight       : %13.9f %13.9f %13.9f\n",
                                                bore[0], bore[1], bore[2] );

                   if ( avseg )
                   {
                      printf( "   Angular velocity: %13.9f %13.9f %13.9f\n",
                                                         av[0], av[1], av[2] );
                   }
                   printf( "\n" );
                }
             }

             return ( 0 );
          }

          When this program was executed on a Mac/Intel/cc/64-bit
          platform, the output was:

          Record:  1
             SCLK time       :           2162686.710986
             Boresight       :  -0.999122830   0.000000000   0.041875654
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  2
             SCLK time       :       54160369751.715164
             Boresight       :  -0.999122830   0.000000000   0.041875654
             Angular velocity:   0.000000000   1.176083393   0.000000000

          Record:  3
             SCLK time       :       54160454948.487686
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  4
             SCLK time       :      299264885854.937805
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  5
             SCLK time       :     2366007685832.532227
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  6
             SCLK time       :     4432750485810.126953
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  7
             SCLK time       :     6505155594828.757812
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  8
             SCLK time       :     8571898394806.352539
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record:  9
             SCLK time       :    10638641194783.947266
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record: 10
             SCLK time       :    12705383994761.541016
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record: 11
             SCLK time       :    14777789103780.169922
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record: 12
             SCLK time       :    16844531903757.763672
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

          Record: 13
             SCLK time       :    18911274703735.359375
             Boresight       :   0.000000000   0.000000000   1.000000000
             Angular velocity:   0.000000000   0.000000000   0.000000000

#### Restrictions

       1)  The binary CK file containing the segment whose descriptor was
           passed to this routine must be opened for read or write access
           by cklpf_c, dafopr_c or dafopw_c.

#### Literature_References

       None.

#### Author_and_Institution

       J. Diaz del Rio     (ODC Space)

#### Version

       -CSPICE Version 1.0.0, 01-NOV-2021 (JDR)

#### Index_Entries

       number of CK type_3 records

#### Link to routine cknr03_c source file cknr03_c.c

    Fri Dec 31 18:41:02 2021