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Index Page wnfltd_c

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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

       wnfltd_c ( Filter small intervals from a DP window )

       void wnfltd_c ( SpiceDouble     smlint,
                       SpiceCell    *  window )

#### Abstract

       Filter (remove) small intervals from a double precision window.

#### Required_Reading

       WINDOWS

#### Keywords

       WINDOWS

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       smlint     I   Limiting measure of small intervals.
       window    I-O  Window to be filtered.

#### Detailed_Input

       smlint      is the limiting measure of the small intervals to be
                   filtered. Intervals of measure less than or equal to
                   `smlint' are removed from the window. The measure `smlint' is
                   signed, and is used as is---the absolute value of `smlint'
                   is not used for in place of negative input values.

       window      on input, 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'.

#### Detailed_Output

       window      on output, is the original window, after small
                   intervals have been removed.

#### Parameters

       None.

#### Exceptions

       1)  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.

       2)  If `smlint' is less than or equal to zero, this routine has
           no effect on the window.

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

#### Files

       None.

#### Particulars

       This routine removes from the input window every interval with
       measure less than or equal to the limiting measure `smlint'.

#### Examples

       The numerical results shown for these examples 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) 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 ]

          remove any intervals equal to or less than 3.0.

          Example code begins here.

          /.
             Program wnfltd_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 ]  [ 29, 29 ]

             into `window'.
             ./
             wninsd_c (  1.0,   3.0, &window );
             wninsd_c (  7.0,  11.0, &window );
             wninsd_c ( 23.0,  27.0, &window );
             wninsd_c ( 29.0,  29.0, &window );

             /.
             Loop over the number of intervals in `window', output
             the `left' and `right' endpoints for each interval.
             ./
             printf( "Initial window:\n" );
             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 );
             }

             /.
             Filter the intervals smaller than or equal to 3.0
             ./
             wnfltd_c ( 3.0, &window );

             /.
             Output the intervals.
             ./
             printf( "\nWindow after filtering intervals <= 3.0:\n" );
             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:

          Initial window:
             Interval 0 [   1.000,    3.000]
             Interval 1 [   7.000,   11.000]
             Interval 2 [  23.000,   27.000]
             Interval 3 [  29.000,   29.000]

          Window after filtering intervals <= 3.0:
             Interval 0 [   7.000,   11.000]
             Interval 1 [  23.000,   27.000]

       2) Using the same window from the first example:

             [ 1.0, 3.0 ]  [ 7.0, 11.0 ]  [ 23.0, 27.0 ]  [ 29.0, 29.0 ]

          Then the following series of calls

             wnfltd_c (  0.0, &window );                             (1)
             wnfltd_c (  2.0, &window );                             (2)
             wnfltd_c (  3.0, &window );                             (3)

          produces the following series of windows

             [ 1.0, 3.0 ]   [ 7.0, 11.0 ]  [ 23.0, 27.0 ]            (1)
                            [ 7.0, 11.0 ]  [ 23.0, 27.0 ]            (2)
                            [ 7.0, 11.0 ]  [ 23.0, 27.0 ]            (3)

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman        (JPL)
       J. Diaz del Rio     (ODC Space)
       H.A. Neilan         (JPL)
       W.L. Taber          (JPL)
       I.M. Underwood      (JPL)

#### Version

       -CSPICE Version 1.1.0, 05-AUG-2021 (JDR)

           Changed input argument name "small" to "smlint" for consistency
           with other routines.

           Edited the header to comply with NAIF standard. Added complete code
           example based on existing example.

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

           Added entry #1 in -Exceptions section.

       -CSPICE Version 1.0.0, 21-JUL-2002 (NJB) (HAN) (WLT) (IMU)

#### Index_Entries

       filter small intervals from a d.p. window

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

    Fri Dec 31 18:41:15 2021