Table of contents
CSPICE_CKNR03 returns the number of pointing instances in a CK type 03
segment. The segment is identified by a CK file handle and segments
descriptor.
Given:
handle the handle of the binary CK file containing the segment.
[1,1] = size(handle); int32 = class(handle)
The file should have been opened for read or write access,
by cspice_cklpf, cspice_dafopr or cspice_dafopw.
descr the packed descriptor of a data type 3 CK segment.
[5,1] = size(descr); double = class(descr)
the call:
[nrec] = cspice_cknr03( handle, descr )
returns:
nrec the number of pointing instances in the type 3 segment.
[1,1] = size(nrec); int32 = class(nrec)
None.
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
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.
function cknr03_ex1()
%
% First load the file (it may also be opened by
% using cspice_cklpf).
%
[handle] = cspice_dafopr( 'VEX_BOOM_V01.BC' );
%
% Begin forward search. Find the first array.
%
cspice_dafbfs( handle );
[found] = cspice_daffna;
%
% Get segment descriptor.
%
% Unpack the segment descriptor into its double precision
% and integer components.
%
[dcd, icd] = cspice_dafgs( 2, 6 );
[descr] = cspice_dafps( dcd, icd );
%
% The data type for a segment is located in the third
% integer component of the descriptor.
%
if ( icd(3) == 3 )
%
% Does the segment contain `av' data?
%
avseg = ( icd(4) == 1 );
%
% How many records does this segment contain?
%
[nrec] = cspice_cknr03( handle, descr );
for i=1:nrec
%
% Get the ith pointing instance in the segment.
%
[record] = cspice_ckgr03( handle, descr, i );
%
% Unpack `record' into the time, quaternion, and av.
%
sclkdp = record(1);
quat = record(2:5);
if ( avseg )
av = record(6:8);
end
%
% The boresight vector is the third row of the
% C-matrix.
%
[cmat] = cspice_q2m( quat );
bore = cmat(3,:);
%
% Write out the results.
%
fprintf( 'Record: %2d\n', i )
fprintf( ' SCLK time : %24.6f\n', sclkdp )
fprintf( ' Boresight : %13.9f %13.9f %13.9f\n', ...
bore )
if ( avseg )
fprintf( ' Angular velocity: %13.9f %13.9f %13.9f\n', ...
av )
end
fprintf( '\n' )
end
end
When this program was executed on a Mac/Intel/Octave6.x/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
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 cspice_ckgr03 which returns the Ith pointing instance
in the segment.
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.
4) If any of the input arguments, `handle' or `descr', is
undefined, an error is signaled by the Matlab error handling
system.
5) If any of the input arguments, `handle' or `descr', is not of
the expected type, or it does not have the expected dimensions
and size, an error is signaled by the Mice interface.
The CK file specified by `handle' should be open for read or
write access.
1) The binary CK file containing the segment whose descriptor was
passed to this routine must be opened for read or write access
by cspice_cklpf, cspice_dafopr or cspice_dafopw.
CK.REQ
DAF.REQ
MICE.REQ
None.
J. Diaz del Rio (ODC Space)
-Mice Version 1.0.0, 01-NOV-2021 (JDR)
number of CK type_3 records
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