DSWAP(3)        BLAS routine of NEC Numeric Library Collection        DSWAP(3)



NAME
       DSWAP - BLAS level one, Swaps two double precision vectors

SYNOPSIS
       SUBROUTINE DSWAP    ( n, x, incx, y, incy )

           INTEGER           n, incx, incy

           DOUBLE PRECISION  x, y


DESCRIPTION
       DSWAP  swaps  two double precision vectors, it interchanges n values of
       vector x and vector y.  incx and incy specify the increment between two
       consecutive elements of respectively vector x and y.


       This routine performs the following vector operation:

                 x <-> y

            where x and y are double precision vectors.

ARGUMENTS
       n       INTEGER. (input)
               Number of vector elements to be swapped.
               If n <= 0, this routine returns without computation.

       x       DOUBLE PRECISION, (input and output)
               Array of dimension (n-1) * |incx| + 1.

       incx    INTEGER. (input)
               Increment between elements of x.
               If incx = 0, the results will be unpredictable.

       y       DOUBLE PRECISION, (input and output)
               array of dimension (n-1) * |incy| + 1. Vector to be swapped.

       incy    INTEGER. (input)
               Increment between elements of y.  If incy = 0, the results will
               be unpredictable.

NOTES
       This routine is Level 1  Basic  Linear  Algebra  Subprograms  (Level  1
       BLAS).

       When  working  backward  (incx < 0 or incy < 0), each routine starts at
       the end of the vector and moves backward, as follows:

            x(1-incx * (n-1)), x(1-incx * (n-2)), ..., x(1)

            y(1-incy * (n-1)), y(1-incy * (n-2)), ..., y(1)



BLAS routine                                                          DSWAP(3)