Procedure

     VALIDI ( Validate an integer set )

     SUBROUTINE VALIDI ( SIZE, N, A )

Abstract

     Create a valid set from an integer set array.

Required_Reading

     SETS

Keywords

     CELLS
     SETS

Declarations

     IMPLICIT NONE

     INTEGER               LBCELL
     PARAMETER           ( LBCELL = -5 )

     INTEGER            SIZE
     INTEGER            N
     INTEGER            A       ( LBCELL:* )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     SIZE       I   Size (maximum cardinality) of the set.
     N          I   Initial no. of (possibly non-distinct) elements.
     A         I-O  Set to be validated.

Detailed_Input

     SIZE     is the maximum cardinality (number of elements)
              of the set.

     N        is the number of (possibly non-distinct) elements
              initially contained in the array used to maintain
              the set. N cannot be greater than the size of the
              set.


     A        is a set.


              On input, A contains N elements beginning at A(1).
              To create a valid set, the elements are ordered,
              and duplicate elements are removed. The contents
              of A(LBCELL) through A(0) are lost during validation.

Detailed_Output

     A        on output, is the set containing the ordered,
              distinct values in the input array, ready for
              use with other set routines.

Parameters

     None.

Exceptions

     1)  If the size of the set is too small to hold the set BEFORE
         validation, the error SPICE(INVALIDSIZE) is signaled. The set
         A is not modified.

Files

     None.

Particulars

     This routine is typically used to turn an array which has been
     initialized through DATA or I/O statements into a set, which
     can then be used with the other set routines.

     Because a set is ordered and contains distinct values, to
     create a set from an array, it is necessary to sort the array
     into the set and remove duplicates. Once the array has been
     sorted, duplicate elements (adjacent after sorting) are removed.
     The size and cardinality of the set are initialized, and the
     set is ready to go.

     Because validation is done in place, there is no chance of
     overflow.

Examples

     Empty sets may be initialized with the cell routines SSIZEx.
     Sets may also be initialized from nonempty set arrays.
     This process, called validation, is done by the set routines
     VALIDC, VALIDD, and VALIDI. In the following example,

           INTEGER      BODIES  ( LBCELL:100 )

           DATA       ( BODIES(I), I=1,8)       /  3, 301,
          .                                        3, 399,
          .                                        5, 501,
          .                                        6, 601,  /

           CALL VALIDI ( 100, 8, BODIES )

     the integer set BODIES is validated. The size of BODIES set to
     100. The eight elements of the array (stored in elements 1-8)
     are sorted, and duplicate elements (in this case, the number 3,
     which appears twice) are removed, and the cardinality of the set
     is set to the number of distinct elements, now seven. The set is
     now ready for use with the rest of the set routines.

     The previous contents of elements LBCELL through 0 are lost
     during the process of validation.

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

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

Version

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

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.0.1, 10-MAR-1992 (WLT)

        Comment section for permuted index source lines was added
        following the header.

    SPICELIB Version 1.0.0, 31-JAN-1990 (CAC) (WLT) (IMU) (NJB)