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Index Page wnfetd_c

Table of contents

Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       wnfetd_c ( Fetch an interval from a DP window )

       void wnfetd_c ( SpiceCell    * window,
                       SpiceInt       n,
                       SpiceDouble  * left,
                       SpiceDouble  * right   )

#### Abstract

       Fetch a particular interval from a double precision window.

#### Required_Reading

       WINDOWS

#### Keywords

       WINDOWS

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       window     I   Input window.
       n          I   Index of interval to be fetched.
       left,
       right      O   Left, right endpoints of the nth interval.

#### Detailed_Input

       window      is a window containing zero or more intervals.

                   `window' must be declared as a double precision SpiceCell.

                   CSPICE provides the following macro, which declares and
                   initializes the cell

                      SPICEDOUBLE_CELL        ( window, WINDOWSZ );

                   where WINDOWSZ is the maximum capacity of `window'.

       n           is the index of a particular interval within the window.
                   Indices range from 0 to NINT-1, where NINT is the number of
                   intervals in the window (card_c(&window)/2).

#### Detailed_Output

       left,
       right       are the left and right endpoints of the N'th interval in
                   the input window. If the interval is not found, `left' and
                   `right' are not defined.

#### Parameters

       None.

#### Exceptions

       1)  If `n' is less than one, the error SPICE(NOINTERVAL) is
           signaled by a routine in the call tree of this routine.

       2)  If the interval does not exist, i.e. n > card_c(window)/2, the
           error SPICE(NOINTERVAL) is signaled by a routine in the call
           tree of this routine.

       3)  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.

       4)  If the `window' cell argument has a type other than
           SpiceDouble, the error SPICE(TYPEMISMATCH) is signaled.

#### Files

       None.

#### Particulars

       None.

#### Examples

       The numerical results shown for this example may differ across
       platforms. The results depend on the SPICE kernels used as input,
       the compiler and supporting libraries, and the machine specific
       arithmetic implementation.

       1) The following code example demonstrates how to insert an
          interval into an existing double precision SPICE window, and
          how to loop over all its intervals to extract their left and
          right points.

          Example code begins here.

          /.
             Program wnfetd_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main()
          {

             /.
             Local parameters.
             ./
             #define WNSIZE          10

             /.
             Local variables.
             ./
             SpiceDouble              left;
             SpiceDouble              right;

             SPICEDOUBLE_CELL ( window,  WNSIZE );

             SpiceInt                 i;

             /.
             Validate the window with size WNSIZE and zero elements.
             ./
             wnvald_c ( WNSIZE, 0, &window );

             /.
             Insert the intervals

                [ 1, 3 ]  [ 7, 11 ]  [ 23, 27 ]

             into `window'.
             ./
             wninsd_c (  1.0,   3.0, &window );
             wninsd_c (  7.0,  11.0, &window );
             wninsd_c ( 23.0,  27.0, &window );

             /.
             Loop over the number of intervals in `window', output
             the `left' and `right' endpoints for each interval.
             ./
             for ( i=0; i<wncard_c(&window); i++)
             {
                wnfetd_c( &window, i, &left, &right );
                printf("Interval %d [%8.3f, %8.3f]\n", i, left, right );
             }

             return ( 0 );

          }

          When this program was executed on a Mac/Intel/cc/64-bit
          platform, the output was:

          Interval 0 [   1.000,    3.000]
          Interval 1 [   7.000,   11.000]
          Interval 2 [  23.000,   27.000]

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman        (JPL)
       J. Diaz del Rio     (ODC Space)
       W.L. Taber          (JPL)
       I.M. Underwood      (JPL)
       E.D. Wright         (JPL)

#### Version

       -CSPICE Version 1.0.2, 10-AUG-2021 (JDR)

           Edited the header to comply to NAIF standard. Added complete code
           example, problem statement and solution.

           Extended description of argument "window" in -Detailed_Input to include
           type and preferred declaration method.

           Added entry #3 in -Exceptions section.

       -CSPICE Version 1.0.1, 30-JUL-2007 (EDW)

          Removed erroneous description in the -Examples section
          indicating "Undefined" as a return state after an error
          event caused by an invalid value of n.

       -CSPICE Version 1.0.0, 22-AUG-2002 (NJB) (WLT) (IMU)

#### Index_Entries

       fetch an interval from a d.p. window

#### Link to routine wnfetd_c source file wnfetd_c.c

    Fri Dec 31 18:41:15 2021