Procedure

   elemi_c ( Element of an integer set ) 

   SpiceBoolean elemi_c ( SpiceInt        item,
                          SpiceCell     * a    )

Abstract

   Determine whether an item is an element of an integer set.

Required_Reading

   SETS

Keywords

   CELLS
   SETS

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   item       I   Item to be tested.
   a          I   Set to be tested.

   The function returns SPICETRUE if `item' is an element of `a'.

Detailed_Input

   item        is an item which may or may not be an element of
               the input set.

   a           is a SPICE set.

               `a' must be declared as an integer SpiceCell.

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

                  SPICEINT_CELL           ( a, ASZ );

               where ASZ is the maximum capacity of `a'.

Detailed_Output

   The function returns SPICETRUE if `item' is a member of the set `a',
   and returns SPICEFALSE otherwise.

Parameters

   None.

Exceptions

   1)  If the `a' cell argument has a type other than SpiceInt, the
       error SPICE(TYPEMISMATCH) is signaled. The function returns
       the value SPICEFALSE.

   2)  If the `a' cell argument does not qualify as a SPICE set, the
       error SPICE(NOTASET) is signaled. SPICE sets have their data
       elements stored in increasing order and contain no duplicate
       elements. The function returns the value SPICEFALSE.

Files

   None.

Particulars

   This routine uses a binary search to check for the presence in the set
   of the specified item.

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) Check if the elements of a list of integers belong to a given
      integer set.

      Example code begins here.


      /.
         Program elemi_ex1
      ./
      #include <stdio.h>
      #include "SpiceUsr.h"

      int main( )
      {

         /.
         Local constants.
         ./
         #define LISTSZ       6
         #define SETDIM       8

         /.
         Local variables.
         ./
         SPICEINT_CELL      ( a     , SETDIM );
         SpiceInt             i;

         /.
         Set the values of the set and the list of integers.
         ./
         SpiceInt             values [SETDIM] = {
                                            -1, 0, 1, 1, 3, 5, 0, -3 };

         SpiceInt             items  [LISTSZ] = { 6, -1, 0, 2, 3, -2 };

         /.
         Add the values to the integer set using appndi_c. The
         results of these calls results in a cell which does not
         qualify as a set.
         ./
         for ( i = 0; i < SETDIM; i++ )
         {
            appndi_c ( values[i], &a );
         }

         /.
         Initialize the set by validating the cell: remove duplicates
         and sort the elements in increasing order.
         ./
         valid_c ( SETDIM, SETDIM, &a );

         /.
         Check if the items in the list belong to the set.
         ./
         for ( i = 0; i < LISTSZ; i++ )
         {
            if ( elemi_c ( items[i], &a ) )
            {
               printf( "Item %4d is in the set.\n", items[i] );
            }
            else
            {
               printf( "Item %4d is NOT in the set.\n", items[i] );
            }
         }

         return ( 0 );
      }


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


      Item    6 is NOT in the set.
      Item   -1 is in the set.
      Item    0 is in the set.
      Item    2 is NOT in the set.
      Item    3 is in the set.
      Item   -2 is NOT in the set.

Restrictions

   None.

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   C.A. Curzon         (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, 24-AUG-2021 (JDR)

       Changed the argument name "set" to "a" for consistency with other
       routines.

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

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

   -CSPICE Version 1.0.0, 07-AUG-2002 (NJB) (CAC) (HAN) (WLT) (IMU)

Index_Entries

   element of an integer set