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 cknr02_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

       cknr02_c ( C-kernel, number of records, type 02 )

       void cknr02_c ( SpiceInt            handle,
                       ConstSpiceDouble    descr  [],
                       SpiceInt          * nrec      )

#### Abstract

       Return the number of pointing records in a CK type 02 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 2 segment.
       nrec       O   The number of records 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 2 CK segment.

#### Detailed_Output

       nrec        is the number of pointing records in the type 2 segment
                   associated with `handle' and `descr'.

#### Parameters

       None.

#### Exceptions

       1)  If the segment indicated by `descr' is not a type 2 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 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 2
       segment, see the CK required reading.

       This routine returns the number of pointing records contained
       in the specified segment. It is normally used in conjunction
       with ckgr02_c, which returns the Ith record 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 start and end SCLK
          time, seconds per tick rate, platform's +Z axis direction,
          and angular velocity vector for each pointing instance in
          the first segment in a CK file that contains segments of data
          type 2.

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

             vo2_swu_ck2.bc

          Example code begins here.

          /.
             Program cknr02_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             SpiceDouble          av     [3];
             SpiceDouble          cmat   [3][3];
             SpiceDouble          dcd    [2];
             SpiceDouble          descr  [5];
             SpiceDouble          quat   [4];
             SpiceDouble          record [10];
             SpiceDouble          sclke;
             SpiceDouble          sclkr;
             SpiceDouble          sclks;
             SpiceDouble          z      [3];

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

             SpiceBoolean         found;

             /.
             First load the file. (The file may also be opened by
             using cklpf_c).
             ./
             dafopr_c ( "vo2_swu_ck2.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] == 2 )
             {

                /.
                How many records does this segment contain?
                ./
                cknr02_c ( handle, descr, &nrec );

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

                   /.
                   Get the ith record in the segment.
                   ./
                   ckgr02_c ( handle, descr, i, record );

                   /.
                   Unpack `record' into the start and end time, rate in
                   TDB seconds/tick, quaternion, and av.
                   ./
                   sclks = record[0];
                   sclke = record[1];
                   sclkr = record[2];

                   moved_c ( record+3, 4, quat );
                   moved_c ( record+7, 3, av );

                   /.
                   The +Z axis direction is the third row of the
                   C-matrix.
                   ./
                   q2m_c ( quat, cmat );

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

                   /.
                   Write out the results.
                   ./
                   printf( "Record: %2d\n", (int)i );
                   printf( "   Start encoded SCLK: %20.6f\n", sclks );
                   printf( "   End encoded SCLK  : %20.6f\n", sclke );
                   printf( "   TDB Seconds/tick  : %20.6f\n", sclkr );
                   printf( "   +Z axis           : %12.8f %12.8f %12.8f\n",
                                                           z[0], z[1], z[2] );
                   printf( "   Angular velocity  : %12.8f %12.8f %12.8f\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
             Start encoded SCLK:   32380393707.000015
             End encoded SCLK  :   32380395707.000015
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.62277152  -0.29420673   0.72498141
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  2
             Start encoded SCLK:   32380402605.999947
             End encoded SCLK  :   32380404605.999947
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.62172600  -0.27894910   0.73187716
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  3
             Start encoded SCLK:   32380412542.000053
             End encoded SCLK  :   32380414542.000053
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.62183610  -0.26307233   0.73764003
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  4
             Start encoded SCLK:   32827264875.000000
             End encoded SCLK  :   32827266875.000000
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.82984105  -0.44796078   0.33270853
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  5
             Start encoded SCLK:   32827403805.999992
             End encoded SCLK  :   32827405805.999992
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.80812500  -0.44911178   0.38109395
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  6
             Start encoded SCLK:   32827412705.000042
             End encoded SCLK  :   32827414705.000042
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.81120505  -0.43593555   0.38975193
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  7
             Start encoded SCLK:   32827417284.000038
             End encoded SCLK  :   32827419284.000038
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.81313834  -0.42861613   0.39382008
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  8
             Start encoded SCLK:   33793314593.000053
             End encoded SCLK  :   33793316593.000053
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.79860617  -0.37840751   0.46801275
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record:  9
             Start encoded SCLK:   33793332478.000046
             End encoded SCLK  :   33793334478.000046
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.77861783  -0.39171670   0.49021658
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 10
             Start encoded SCLK:   33793341463.000061
             End encoded SCLK  :   33793343463.000061
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.76852381  -0.39797437   0.50098659
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 11
             Start encoded SCLK:   33793350363.000034
             End encoded SCLK  :   33793352363.000034
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.75779934  -0.40484364   0.51170478
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 12
             Start encoded SCLK:   33984028250.000000
             End encoded SCLK  :   33984030250.000000
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.77099184  -0.39926339   0.49614546
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 13
             Start encoded SCLK:   33984046134.999992
             End encoded SCLK  :   33984048134.999992
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.75024440  -0.41218993   0.51694564
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 14
             Start encoded SCLK:   33984055121.000053
             End encoded SCLK  :   33984057121.000053
             TDB Seconds/tick  :             0.001000
             +Z axis           :   0.73947359  -0.41886863   0.52699894
             Angular velocity  :   0.00000000   0.00000000   0.00000000

          Record: 15
             Start encoded SCLK:   33984220835.999966

          [...]

          Warning: incomplete output. Only 100 out of 875 lines have been
          provided.

#### 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_2 records

#### Link to routine cknr02_c source file cknr02_c.c

    Fri Dec 31 18:41:02 2021