Procedure

     VSCL ( Vector scaling, 3 dimensions )

     SUBROUTINE VSCL ( S, V1, VOUT )

Abstract

     Multiply a scalar and a double precision 3-dimensional vector.

Required_Reading

     None.

Keywords

     VECTOR

Declarations

     IMPLICIT NONE

     DOUBLE PRECISION   S
     DOUBLE PRECISION   V1   ( 3 )
     DOUBLE PRECISION   VOUT ( 3 )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     S          I   Scalar to multiply a vector.
     V1         I   Vector to be multiplied.
     VOUT       O   Product vector, S * V1.

Detailed_Input

     S        is a double precision scalar used to multiply the vector
              V1.

     V1       is a double precision 3-dimensional vector, which is to
              be scaled by S.

Detailed_Output

     VOUT     is a double precision 3-dimensional vector containing
              the product of the scalar with the vector V1.

Parameters

     None.

Exceptions

     Error free.

Files

     None.

Particulars

     For each value of the index I from 1 to 3, this subroutine
     performs the following multiplication

        VOUT(I) = S * V1(I)

     No error checking is performed to guard against numeric overflow
     or underflow.

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 a sets of scalar double precision values and use them
        to scale a given 3-dimensional vector.


        Example code begins here.


              PROGRAM VSCL_EX1
              IMPLICIT NONE

        C
        C     Local parameters.
        C
              INTEGER               SETSIZ
              PARAMETER           ( SETSIZ = 3 )

        C
        C     Local variables.
        C
              DOUBLE PRECISION      S    ( SETSIZ )
              DOUBLE PRECISION      V1   ( 3      )
              DOUBLE PRECISION      VOUT ( 3      )

              INTEGER               I

        C
        C     Define the set of scalars and the input vector.
        C
              DATA                  S    / 3.D0, 0.D0, -1.D0 /

              DATA                  V1   / 1.D0, 2.D0, -3.D0 /


              WRITE(*,'(A,3F6.1)') 'Input vector : ', V1
              WRITE(*,*)

        C
        C     Calculate product of each scalar and V1.
        C
              DO I=1, SETSIZ

                 CALL VSCL ( S(I), V1, VOUT )

                 WRITE(*,'(A,F6.1)')  'Scale factor : ', S(I)
                 WRITE(*,'(A,3F6.1)') 'Output vector: ', VOUT
                 WRITE(*,*)

              END DO

              END


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


        Input vector :    1.0   2.0  -3.0

        Scale factor :    3.0
        Output vector:    3.0   6.0  -9.0

        Scale factor :    0.0
        Output vector:    0.0   0.0  -0.0

        Scale factor :   -1.0
        Output vector:   -1.0  -2.0   3.0

Restrictions

     1)  The user is responsible for insuring that no floating point
         overflow occurs from multiplying S by any component of V1. No
         error recovery or reporting scheme is incorporated in this
         subroutine.

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, 23-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)