Procedure

     PRODAD ( Product of a double precision array )

     DOUBLE PRECISION FUNCTION  PRODAD ( ARRAY, N )

Abstract

     Return the product of the elements of a double precision array.

Required_Reading

     None.

Keywords

     ARRAY
     MATH
     UTILITY

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION   ARRAY ( * )
     INTEGER            N

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     ARRAY      I   Input array.
     N          I   Number of elements in ARRAY.

     The function returns the product of the elements of ARRAY.

Detailed_Input

     ARRAY    is the input array.

     N        is the number of elements in the array.

Detailed_Output

     The function returns the product of the elements of the input
     array. That is,

        PRODAD = ARRAY(1) * ARRAY(2) * ... * ARRAY(N)

     If N is zero or negative, PRODAD is one.

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     The value of the function is initially set to one. The elements
     of the array are then multiplied. If the number of elements is
     zero or negative, PRODAD is one.

Examples

     Let ARRAY contain the following elements.

           ARRAY(1) = 12.D0
           ARRAY(2) =  2.D0
           ARRAY(3) =  4.D0
           ARRAY(4) = 75.D0
           ARRAY(5) = 18.D0

     Then

           PRODAD ( ARRAY,   -3 )       =      1.D0
           PRODAD ( ARRAY,    0 )       =      1.D0
           PRODAD ( ARRAY,    1 )       =     12.D0
           PRODAD ( ARRAY,    2 )       =     24.D0
           PRODAD ( ARRAY,    5 )       = 129600.D0
           PRODAD ( ARRAY(3), 3 )       =   5400.D0

Restrictions

     1)  PRODAD does not check for overflow.

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, 07-APR-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 (IMU)