Procedure

     VADD ( Vector addition, 3 dimensional )

     SUBROUTINE VADD ( V1, V2, VOUT )

Abstract

     Add two double precision 3-dimensional vectors.

Required_Reading

     None.

Keywords

     VECTOR

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION   V1   ( 3 )
     DOUBLE PRECISION   V2   ( 3 )
     DOUBLE PRECISION   VOUT ( 3 )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     V1         I   First vector to be added.
     V2         I   Second vector to be added.
     VOUT       O   Sum vector, V1 + V2.

Detailed_Input

     V1,
     V2       are two arbitrary double precision 3-dimensional
              vectors.

Detailed_Output

     VOUT     is the double precision 3-dimensional vector sum of V1
              and V2.

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     This routine simply performs addition between components of V1
     and V2. No checking is performed to determine whether floating
     point overflow has occurred.

Examples

     The numerical results shown for this example 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) Define two sets of 3-dimensional vectors and compute the sum
        of each vector in first set with the corresponding vector in
        the second set.


        Example code begins here.


              PROGRAM VADD_EX1
              IMPLICIT NONE

        C
        C     Local parameters.
        C
              INTEGER               SETSIZ
              PARAMETER           ( SETSIZ = 2 )

        C
        C     Local variables.
        C
              DOUBLE PRECISION      SETA ( 3, SETSIZ )
              DOUBLE PRECISION      SETB ( 3, SETSIZ )
              DOUBLE PRECISION      VOUT ( 3 )

              INTEGER               I
              INTEGER               J

        C
        C     Define the two vector sets.
        C
              DATA                  SETA / 1.D0,  2.D0,  3.D0,
             .                             1.D-7, 1.D23, 1.D-9  /

              DATA                  SETB / 4.D0,  5.D0,   6.D0,
             .                             1.D24, 1.D23,  0.D0  /

        C
        C     Calculate the sum of each pair of vectors
        C
              DO I=1, SETSIZ

                 CALL VADD ( SETA(1,I), SETB(1,I), VOUT )

                 WRITE(*,'(A,3E11.2)') 'Vector A  : ',
             .                        ( SETA(J,I), J=1,3 )
                 WRITE(*,'(A,3E11.2)') 'Vector B  : ',
             .                        ( SETB(J,I), J=1,3 )
                 WRITE(*,'(A,3E11.2)') 'Sum vector: ', VOUT
                 WRITE(*,*) ' '

              END DO

              END


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


        Vector A  :    0.10E+01   0.20E+01   0.30E+01
        Vector B  :    0.40E+01   0.50E+01   0.60E+01
        Sum vector:    0.50E+01   0.70E+01   0.90E+01

        Vector A  :    0.10E-06   0.10E+24   0.10E-08
        Vector B  :    0.10E+25   0.10E+24   0.00E+00
        Sum vector:    0.10E+25   0.20E+24   0.10E-08

Restrictions

     1)  The user is required to determine that the magnitude each
         component of the vectors is within the appropriate range so as
         not to cause floating point overflow.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     W.M. Owen          (JPL)
     W.L. Taber         (JPL)

Version

    SPICELIB Version 1.1.0, 06-JUL-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard. Added complete
        code example based on existing example.

    SPICELIB Version 1.0.2, 22-APR-2010 (NJB)

        Header correction: assertions that the output
        can overwrite the input have been removed.

    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 (WMO)