Procedure

     EVEN  ( Is an integer even? )

     LOGICAL FUNCTION EVEN ( IVAL )

Abstract

     Determine whether an integer is even.

Required_Reading

     None.

Keywords

     NUMBERS

Declarations

     IMPLICIT NONE

     INTEGER          IVAL

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     IVAL       I   The integer in question.

     The function returns .TRUE. if IVAL is even, otherwise .FALSE.

Detailed_Input

     IVAL     is the integer to be tested for evenness.

Detailed_Output

     The function returns .TRUE. if IVAL is even, .FALSE. if IVAL is
     odd.

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     None.

Examples

     Let ENDPTS contain a series of endpoints,

        a , b , ..., a , b
         1   1        n   n

     representing an ordered collection of disjoint intervals,

        a   <  b   < a
         i  -   i     i+1

     The following code fragment uses EVEN to determine whether
     an arbitrary value X is contained in any of the intervals.

        CONTAINED = .FALSE.

        DO I = 1, N-1
           IF ( X .GE. ENDPTS(I)  .AND.  X .LE. ENDPTS(I+1) ) THEN
              CONTAINED = ( .NOT. EVEN ( I ) )
           END IF
        END DO

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)

Version

    SPICELIB Version 1.1.0, 08-APR-2021 (JDR)

        Added IMPLICIT NONE statement.

        Changed the input argument name "I" to "IVAL" for consistency
        with other routines.

        Edited the header to comply with NAIF standard. Removed
        unnecessary $Revisions section.

    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 (IMU)