Table of contents
CSPICE_WNRELD compares two double precision windows.
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.
op a comparison operator, indicating the way in which the input
sets are to be compared.
help, op
STRING = Scalar
`op' may be any of the following:
Operator Meaning
-------- -------------------------------------------
'=' a = b is True if `a' and `b' are equal
(contain the same intervals).
'<>' a <> b is True if `a' and `b' are not equal.
'<=' a <= b is True if `a' is a subset of `b'.
'<' a < b is True if `a' is a proper subset
of `b'.
'>=' a >= b is True if `b' is a subset of `a'.
'>' a > b is True if `b' is a proper subset
of `a'.
the call:
wnreld = cspice_wnreld( a, op, b )
returns:
wnreld the result of the comparison.
help, wnreld
BOOLEAN = Scalar
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
[ 1, 2 ] [ 9, 9 ] [ 24, 27 ]
Compare `a' and `b' and find out if `a' and `'b are equal or not,
if `a' is a subset or a proper subset of `b', or if `b' is a
subset or a proper subset of `a'.
Example code begins here.
PRO wnreld_ex1
;;
;; Create a cell containing a double precision
;; 8-vector.
;;
win1 = cspice_celld( 8 )
win2 = cspice_celld( 8 )
;;
;; Define two window with three intervals.
;;
darray = [ [ 1.d, 3.0], [ 7.0, 11.0], [23.0, 27.0] ]
;;
;; Add the window data to the cell.
;;
for i=0, 2 do begin
cspice_wninsd, darray[0,i], darray[1,i], win1
endfor
darray = [ [ 1.d, 2.0], [ 9.0, 9.0], [24.0, 27.0] ]
;;
;; Add the window data to the cell.
;;
for i=0, 2 do begin
cspice_wninsd, darray[0,i], darray[1,i], win2
endfor
ops = [ '=', '<>', '<=', '<', '>=', '>' ]
;;
;; Loop over each operation token in 'ops', apply that
;; operation to 'win1' and 'win2'.
;;
for i=0, n_elements(ops) -1 do begin
if( cspice_wnreld( win1, ops[i], win2 ) ) then begin
print, "`a' ", ops[i], " `b' is True"
endif else begin
print, "`a' ", ops[i], " `b' is False"
endelse
endfor
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
`a' = `b' is False
`a' <> `b' is True
`a' <= `b' is False
`a' < `b' is False
`a' >= `b' is True
`a' > `b' is True
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 function returns True whenever the specified relationship
between the input windows `a' and `b' is satisfied. For example,
the expression
cspice_wnreld ( needed, '<=', avail )
is True whenever the window `needed' is a subset of the window
`avail'. One window is a subset of another window if each of
the intervals in the first window is included in one of the
intervals in the second window. In addition, the first window
is a proper subset of the second if the second window contains
at least one point not contained in the first window. (Thus,
'<' implies '<=', and '>' implies '>='.)
The following pairs of expressions are equivalent.
cspice_wnreld ( a, '>', b )
cspice_wnreld ( b, '<', a )
cspice_wnreld ( a, '>=', b )
cspice_wnreld ( b, '<=', a )
1) If the relational operator is not recognized, the error
SPICE(INVALIDOPERATION) 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', `op' or `b', is undefined,
an error is signaled by the IDL error handling system.
4) If any of the input arguments, `a', `op' or `b', 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 1.0.2, 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 and reformatted example's output.
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 1.0.1, 12-SEP-2006 (EDW)
Correct Required Reading citation cell.req to cells.req.
-Icy Version 1.0.0, 08-AUG-2004 (EDW)
compare two d.p. windows
|