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Index Page card_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

       card_c ( Cardinality of a cell )

       SpiceInt card_c ( SpiceCell  * cell )

#### Abstract

       Return the cardinality (current number of elements) in a
       cell of any data type.

#### Required_Reading

       CELLS
       SETS
       WINDOWS

#### Keywords

       CELLS
       SETS
       WINDOWS

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       cell       I   Input cell.

       The function returns the cardinality of the input cell.

#### Detailed_Input

       cell        is a SPICE cell of character, double precision, or integer data
                   type.

                   `cell' must be declared as a character, double precision or
                   integer SpiceCell.

                   CSPICE provides the following macros, which declare and
                   initialize the cell

                      SPICECHAR_CELL          ( cell, CELLSZ, CELLMLEN );
                      SPICEDOUBLE_CELL        ( cell, CELLSZ );
                      SPICEINT_CELL           ( cell, CELLSZ );

                   where CELLSZ is the maximum capacity of `cell' and CELLMLEN is
                   the maximum length of any member in the character cell.

#### Detailed_Output

       The function returns the cardinality of (current number of elements in) the
       input cell.

#### Parameters

       None.

#### Exceptions

       1)  If the input cell has invalid cardinality, the error
           SPICE(INVALIDCARDINALITY) is signaled. card_c returns an
           unspecified value in this case.

       2)  If the input cell has invalid size, the error SPICE(INVALIDSIZE)
           is signaled. card_c returns an unspecified value in this case.

       3)  If the input cell does not have a recognized data type, the error
           SPICE(NOTSUPPORTED) is signaled by a routine in the call tree of
           this routine. card_c returns an unspecified value in this case.

#### Files

       None.

#### Particulars

       This is a generic function which may be used on SpiceCells of
       character, double precision, or integer data type.

#### 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) The size_c function is typically used in conjunction
          with the card_c function to predict (and subsequently
          avoid) overflows when manipulating cells. In the following
          example, card_c and size_c are used to determine whether
          the union of two sets is safe.

          Example code begins here.

          /.
             Program card_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local constants.
             ./
             #define SETDIM       5

             /.
             Local variables.

             Declare two SPICE cells.
             ./
             SPICEINT_CELL      ( seta, SETDIM );
             SPICEINT_CELL      ( setb, SETDIM );
             SPICEINT_CELL      ( setc, SETDIM );

             SpiceInt             i;

             /.
             Create a list of items and even numbers.
             ./
             SpiceInt             even   [SETDIM] = {  0,  2,  4,  4,  8 };

             SpiceInt             items  [SETDIM] = {  0,  1,  1,  2,  8 };

             /.
             Initialize the empty sets.
             ./
             valid_c ( SETDIM, 0, &seta );
             valid_c ( SETDIM, 0, &setb );

             /.
             Insert `even' on `seta' and `items' on `setb'
             ./
             for ( i = 0; i < SETDIM; i++ )
             {
                insrti_c ( even[i],  &seta );
                insrti_c ( items[i], &setb );
             }

             /.
             Perform the union if possible.
             ./
             if ( card_c ( &seta ) + card_c ( &setb ) <= size_c ( &setc ) )
             {
                printf( "Union will not overflow the output set.\n" );
                union_c ( &seta, &setb, &setc );
             }
             else
             {
                printf( "Union may overflow...\n" );
                inter_c ( &seta, &setb, &setc );

                if ( card_c ( &seta ) + card_c ( &setb ) - card_c ( &setc ) <=
                     size_c ( &setc ) )
                {
                   printf( "   ... but inter_c indicates it is safe!\n" );
                   union_c ( &seta, &setb, &setc );
                }
                else
                {
                   printf( "  ... and inter_c confirms it!\n" );
                }

             }

             return ( 0 );
          }

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

          Union may overflow...
             ... but inter_c indicates it is safe!

       2) The cardinality function cspice_card is also typically used to
          process each of the elements of a cell, set or window. In this
          example, we will build a double precision cell via a series of
          calls to appndd_c. Create a set from this set by calling
          valid_c and display the results.

          Example code begins here.

          /.
             Program card_ex2
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main()
          {
             /.
             Local parameters.

             SETSIZ is the maximum capacity of the set.
             ./
             #define SETSIZ          1000000

             /.
             INISIZ will be the initial number of elements in the set.
             ./
             #define INISIZ          10

             /.
             Declare the set.
             ./
             SPICEDOUBLE_CELL ( dpSet, SETSIZ );

             /.
             Other local variables.
             ./
             SpiceDouble             item;

             SpiceInt                i;

             /.
             Initialize the cell's data array.  We use bogus values to
             simplify the example.
             ./
             for ( i = INISIZ-1;  i >= 0;  i-- )
             {
                appndd_c (  (SpiceDouble)(i),  &dpSet  );
             }

             printf( "Initial cell:\n" );
             for ( i = 0; i < card_c( &dpSet ); i++ )
             {
                item  =  SPICE_CELL_ELEM_D( &dpSet, i );
                printf( "  %f\n", item );
             }

             /.
             After the append, does the cell key as a set?
             ./
             if ( dpSet.isSet )
             {
                printf( "Cell is a set after append.\n" );
             }
             else
             {
                printf( "Cell is not a set after append.\n" );
             }

             /.
             Validate the set.  The elements of the set will be arranged
             in increasing order after this call.
             ./
             valid_c ( SETSIZ, INISIZ, &dpSet );

             /.
             Output the elements of the set.
             ./
             printf( "Cell after valid_c call:\n" );
             for ( i = 0; i < card_c( &dpSet ); i++ )
             {
                item  =  SPICE_CELL_ELEM_D( &dpSet, i );
                printf( "  %f\n", item );
             }

             /.
             After the valid_c call, does the cell key as a set?
             ./
             if ( dpSet.isSet )
             {
                printf( "Cell is a set after validate.\n" );
             }
             else
             {
                printf( "Cell is not a set after validate.\n" );
             }

             return ( 0 );
          }

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

          Initial cell:
            9.000000
            8.000000
            7.000000
            6.000000
            5.000000
            4.000000
            3.000000
            2.000000
            1.000000
            0.000000
          Cell is not a set after append.
          Cell after valid_c call:
            0.000000
            1.000000
            2.000000
            3.000000
            4.000000
            5.000000
            6.000000
            7.000000
            8.000000
            9.000000
          Cell is a set after validate.

#### 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 1.0.1, 27-AUG-2021 (JDR)

           Edited the header to comply with NAIF standard. Added complete
           code examples; first one based on existing example fragments.

           Added SETS and WINDOWS to the list of required readings and
           keywords.

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

           Added entry #3 to -Exceptions section.

       -CSPICE Version 1.0.0, 06-AUG-2002 (NJB) (CAC) (HAN) (WLT) (IMU)

#### Index_Entries

       cardinality of an integer cell

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

    Fri Dec 31 18:41:02 2021