Table of contents
CSPICE_WNEXTD extracts the left or right endpoints from
a double precision window.
Given:
side a scalar character that indicates whether the left or right
endpoints of the intervals in the window are to be extracted.
help, side
STRING = Scalar
'L', 'l' Left endpoints.
'R', 'r' Right endpoints.
If 'side' is not recognized, the input window is
not changed.
window a scalar, double precision window containing zero or more
intervals.
help, window
STRUCT = cspice_celld(2*N)
'window' must be created as a window structure via a
cspice_celld call.
the call:
cspice_wnextd, side, window
returns:
window on output, is the collection of singleton intervals containing
either the left or the right endpoints of the intervals in the
original window.
help, window
STRUCT = cspice_celld(2*N)
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) Given a double precision window, containing the following four
intervals:
[ 1.0, 3.0 ], [ 7.0, 11.0 ], [ 23.0, 27.0 ], [29.0, 29.0]
extract all its left endpoints and output the resulting
singleton intervals.
Example code begins here.
PRO wnextd_ex1
;;
;; Create a cell containing a double
;; precision 8-vector.
;;
win1 = cspice_celld( 8 )
;;
;; Define a window with four intervals.
;;
darray = [ [ 1.d, 3.0], [ 7.0, 11.0], [23.0, 27.0], [29.d, 29.d] ]
;;
;; Add the window data to the cell.
;;
for i=0, 3 do begin
cspice_wninsd, darray[0,i], darray[1,i], win1
endfor
;;
;; Extract left endpoints:
;;
cspice_wnextd, 'L', win1
;;
;; Calculate the number of intervals in the
;; return window 'win1'.
;;
no_intervals = cspice_wncard(win1)
;;
;; Output the intervals.
;;
for i= 0, (no_intervals -1 ) do begin
cspice_wnfetd, win1, 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 1.0000000
7.0000000 7.0000000
23.000000 23.000000
29.000000 29.000000
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.
This routine replaces every interval in the input window with
the singleton interval containing one of the endpoints of the
interval.
1) If the endpoint specification, `side', is not recognized, the
error SPICE(INVALIDENDPNTSPEC) is signaled by a routine in the
call tree of this routine.
2) The cardinality of the input `window' 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, `side' or `window', is
undefined, an error is signaled by the IDL error handling
system.
4) If any of the input arguments, `side' or `window', 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, 10-AUG-2021 (JDR)
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.
Added arguments' type and size information in the -I/O 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)
extract the endpoints from a d.p. window
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