Index Page ordi_c

A B C D E F G H I J K L M N O P Q R S T U V W X

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

       SpiceInt ordi_c ( SpiceInt        item,
                         SpiceCell     * set   )

#### Abstract

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

#### Required_Reading

       SETS

#### Keywords

       SEARCH
       SETS

#### Brief_I/O

       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.

#### Detailed_Input

       item      is an integer to be located within a set.

       set       is an integer CSPICE set that is to be searched for the
                 occurrence of item.

                 set must be declared as an integer SpiceCell.

#### Detailed_Output

       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.

#### Parameters

       None.

#### Exceptions

       1) If the input set argument is a SpiceCell of type other than
          integer, 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.

#### Files

       None.

#### Particulars

       A natural ordering can be imposed upon 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

#### Examples

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

             #include "SpiceUsr.h"

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

                SPICEINT_CELL ( set,   MAXSIZ );

                SpiceInt               inputs [MAXSIZ] =
                                       {
                                          8, 1, 2, 9, 7, 4, 10
                                       };

                SpiceInt               expected [MAXSIZ] =
                                       {
                                          4, 0, 1, 5, 3, 2, 6
                                       };

                SpiceInt               i;
                SpiceInt               iElt;

                /.
                Create the set.
                ./

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

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

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

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

                return ( 0 );
             }

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

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

#### Version

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

#### Index_Entries

       the ordinal position of an element in a set

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

    Wed Apr  5 17:54:40 2017