The function returns the ordinal position of any given item in a
   double precision set.  If the item does not appear in the set, the
   function returns -1.

   SETS 

   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   item       I   An item to locate within a set. 
   set        I   A set to search for a given item. 

   The function returns the ordinal position of item within the set. 

   item      is a double precision number to be located within a set. 

   set       is a double precision CSPICE set that is to be searched
             for the occurrence of item.

             set must be declared as a double precision SpiceCell.

   The function returns the ordinal position of item within set. 
   Ordinal positions range from 0 to N-1, where N is the cardinality
   of the set.

   If item is not an element of set, the function returns -1. 

   None. 

   A natural ordering can be imposed upon the the elements of any 
   CSPICE set, be it integer, character or double precision.  For 
   character strings the ASCII collating sequence serves as the 
   ordering relation, for double precision and integer variables 
   the arithmetic ordering is used. 

   Given any element of a set, its location within this ordered 
   sequence of elements is called its ordinal position within 
   the set. 

   In common mathematical usage, ordinal positions of elements
   in a set of cardinality N range from 1 to N.  In C programs,
   it is much more convenient to use the range 0 to N-1; this is
   the convention used in CSPICE.

   For illustrative purposes suppose that set represents the set 

      { 8, 1, 2, 9, 7, 4, 10 } 

   The ordinal position of:    

       8 is 4 
       1 is 0 
       2 is 1 
       9 is 5 
       7 is 3 
       4 is 2 
      10 is 6 

   1) Obtain the ordinal positions shown in the table of the Particulars
      section above.


         #include "SpiceUsr.h"

         int main()
         {
            /.
            Declare a double precision set and populate it with 
            the elements shown above.
            ./
            #define MAXSIZ         7

            SPICEDOUBLE_CELL ( set, MAXSIZ );

            SpiceDouble            inputs [MAXSIZ] = 
                                   {
                                      8.0, 1.0, 2.0, 9.0, 7.0, 4.0, 10.0
                                   };

            SpiceDouble            expected [MAXSIZ] = 
                                   {
                                      4.0, 0.0, 1.0, 5.0, 3.0, 2.0, 6.0
                                   };

            SpiceInt               i;
            SpiceDouble            dElt;


            /.
            Create the set.
            ./

            for ( i = 0;  i < MAXSIZ;  i++ )
            {
               insrtd_c ( inputs[i], &set );
            }

            /.
            Examine the ordinal positions of the set's elements.
            Extract each element and verify that ordd_c gives the
            index at which the element is located.
            ./

            for ( i = 0;  i < card_c(&set);  i++ )
            {
               dElt = inputs[i];

               if (  ordd_c(dElt, &set)  !=  expected[i]  )
               {
                  setmsg_c ( "Position of # was expected to be # "
                             "but was actually #."                 );
                  errdp_c  ( "#",  dElt                            );
                  errdp_c  ( "#",  expected[i]                     );
                  errint_c ( "#",  ordd_c(dElt,&set)               );
                  sigerr_c ( "INVALID LOCATION"                    );
               }
            }

            return ( 0 );
         }

   None.

   1) If the input set argument is a SpiceCell of type other than
      double precision, the error SPICE(TYPEMISMATCH) is signaled.

   2) If the input set argument does not qualify as a CSPICE set, 
      the error SPICE(NOTASET) will be signaled.  CSPICE sets have
      their data elements sorted in increasing order and contain
      no duplicate data elements.

   None. 

   N.J. Bachman    (JPL) 
   C.A. Curzon     (JPL) 
   H.A. Neilan     (JPL) 
   W.L. Taber      (JPL) 
   I.M. Underwood  (JPL) 

   None. 

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

   the ordinal position of an element in a set