Table of contents
CSPICE_DAFPS packs (assembles) an array summary from its double precision
and integer components.
Given:
dc the double precision components of the summary.
help, dc
DOUBLE = Array[ND]
ic the integer components of the summary.
help, ic
LONG = Array[NI]
the call:
cspice_dafps, dc, ic, sum
returns:
sum an array summary containing the components in `dc' and `ic'.
help, sum
DOUBLE = Array[N]
This identifies the contents and location of a single array
within a DAF.
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.
PRO cknr03_ex1
;;
;; First load the file (it may also be opened by using
;; cspice_cklpf).
;;
cspice_dafopr, 'VEX_BOOM_V01.BC', handle
;;
;; Begin forward search. Find the first array.
;;
cspice_dafbfs, handle
cspice_daffna, found
;;
;; Get segment descriptor.
;;
;; Unpack the segment descriptor into its double precision
;; and integer components.
;;
cspice_dafgs, 2L, 6L, dcd, icd
cspice_dafps, dcd, icd, descr
;;
;; The data type for a segment is located in the third
;; integer component of the descriptor.
;;
if ( icd[2] eq 3L ) then begin
;;
;; Does the segment contain `av' data?
;;
avseg = ( icd[3] eq 1L )
;;
;; How many records does this segment contain?
;;
cspice_cknr03, handle, descr, nrec
for i=1L, nrec do begin
;;
;; Get the ith pointing instance in the segment.
;;
cspice_ckgr03, handle, descr, i, record
;;
;; Unpack `record' into the time, quaternion, and av.
;;
sclkdp = record[0]
quat = record[1:4]
if ( avseg ) then begin
av = record[5:7]
endif
;;
;; The boresight vector is the third row of the
;; C-matrix.
;;
cspice_q2m, quat, cmat
bore = cmat[*,2]
;;
;; Write out the results.
;;
print, format='(A,I2)', 'Record: ', i
print, format='(A,F25.6)', ' SCLK time :', sclkdp
print, format='(A,3F14.9)', ' Boresight :', bore
if ( avseg ) then begin
print, format='(A,3F14.9)', ' Angular velocity:', av
endif
print
endfor
endif
END
When this program was executed on a Mac/Intel/IDL8.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
The components of array summaries are packed into double precision arrays
for reasons outlined in the DAF required reading. Two routines,
cspice_dafps (pack summary) and cspice_dafus (unpack summary) are
provided for packing and unpacking summaries.
The total size of the summary is
(NI - 1)
ND + -------- + 1
2
double precision words (where the sizes of `dc' and `ic', ND and NI,
are non-negative).
1) If `nd', the number of double precision components, is zero or
negative, no DP components are stored.
2) If `ni', the number of integer components, is zero or
negative, no integer components are stored.
3) If the total size of the summary is greater than 125 double
precision words, some components may not be stored. See
-Particulars for details.
4) If any of the input arguments, `dc' or `ic', is undefined, an
error is signaled by the IDL error handling system.
5) If any of the input arguments, `dc' or `ic', is not of the
expected type, or it does not have the expected dimensions and
size, an error is signaled by the Icy interface.
6) If the output argument `sum' is not a named variable, an error
is signaled by the Icy interface.
None.
None.
DAF.REQ
ICY.REQ
None.
J. Diaz del Rio (ODC Space)
-Icy Version 1.0.0, 17-NOV-2021 (JDR)
pack DAF summary
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