Table of contents
CSPICE_WNUNID places the union of two double precision
windows into a third window.
Given:
a,
b two SPICE windows, each of which contains zero or more
intervals.
help, a
STRUCT = cspice_celld(2*N)
help, b
STRUCT = cspice_celld(2*M)
The user must create `a' and `b' using cspice_celld.
the call:
cspice_wnunid, a, b, c
returns:
c the output SPICE window, containing the union of `a' and `b'
--- every point contained in `a', or in `b', or in both.
help, c
STRUCT = cspice_celld(2*R)
`c' must be distinct from both `a' and `b'.
The user must create 'c' using cspice_celld.
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) Let `a' contain the intervals
[ 1, 3 ] [ 7, 11 ] [ 23, 27 ]
and `b' contain the intervals
[ 2, 6 ] [ 8, 10 ] [ 16, 18 ]
Compute the union of `a' and `b'.
Example code begins here.
PRO wnunid_ex1
;;
;; Create two cells each containing a double precision
;; 8-vector.
;;
win1 = cspice_celld( 8 )
win2 = cspice_celld( 8 )
win3 = cspice_celld( 8 )
;;
;; Define two windows with three intervals.
;;
darray = [ [ 1.d, 3.d], [ 7.d, 11.d], [23.d, 27.d] ]
;;
;; Add the window data to the cell.
;;
for i=0, 2 do begin
cspice_wninsd, darray[0,i], darray[1,i], win1
endfor
darray2 = [ [ 2.d, 6.d], [ 8.d, 10.d], [16.d, 18.d] ]
;;
;; Add the window data to the cell.
;;
for i=0, 2 do begin
cspice_wninsd, darray2[0,i], darray2[1,i], win2
endfor
;;
;; Do the union.
;;
cspice_wnunid, win1, win2, win3
;;
;; Calculate the number of intervals in the
;; return window 'win1'.
;;
no_intervals = cspice_wncard(win3)
;;
;; Output the intervals.
;;
for i= 0, (no_intervals -1 ) do begin
cspice_wnfetd, win3, i, left, right
print, left, right
endfor
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
1.0000000 6.0000000
7.0000000 11.000000
16.000000 18.000000
23.000000 27.000000
The user must create any needed window structures with
cspice_celld prior to use regardless of whether the routine
uses the window as input or returns it as output.
The union of two windows contains every point contained in the
first window, or the second window, or both.
1) If the union of the two windows results in an excess of
elements, the error SPICE(WINDOWEXCESS) is signaled by a
routine in the call tree of this routine.
2) The cardinality of the input windows must be even. Left
endpoints of stored intervals must be strictly greater than
preceding right endpoints. Right endpoints must be greater
than or equal to corresponding left endpoints. Invalid window
data are not diagnosed by this routine and may lead to
unpredictable results.
3) If any of the input arguments, `a', `b' or `c', is undefined,
an error is signaled by the IDL error handling system.
4) If any of the input arguments, `a', `b' or `c', is not of the
expected type, or it does not have the expected dimensions and
size, an error is signaled by the Icy interface.
None.
None.
ICY.REQ
CELLS.REQ
WINDOWS.REQ
None.
J. Diaz del Rio (ODC Space)
E.D. Wright (JPL)
-Icy Version 1.0.3, 24-AUG-2021 (JDR)
Added arguments' type and size information in the -I/O section.
Edited the header to comply with NAIF standard. Added
example's problem statement.
Extended -Particulars section.
Added -Parameters, -Exceptions, -Files, -Restrictions,
-Literature_References and -Author_and_Institution sections.
Removed reference to the routine's corresponding CSPICE header from
-Abstract section.
-Icy Version 1.0.2, 26-NOV-2007 (EDW)
Implemented use of cspice_wncard function to return
window cardinality.
-Icy Version 1.0.1, 12-SEP-2006 (EDW)
Correct Required Reading citation cell.req to cells.req.
-Icy Version 1.0.0, 08-AUG-2004 (EDW)
union two d.p. windows
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