stdlib_cswap Subroutine

     pure subroutine stdlib_cswap(n,cx,incx,cy,incy)
     !! CSWAP interchanges two vectors.
        ! -- reference blas level1 routine --
        ! -- reference blas is a software package provided by univ. of tennessee,    --
        ! -- univ. of california berkeley, univ. of colorado denver and nag ltd..--
           ! Scalar Arguments 
           integer(ilp), intent(in) :: incx, incy, n
           ! Array Arguments 
           complex(sp), intent(inout) :: cx(*), cy(*)
        ! =====================================================================
           ! Local Scalars 
           complex(sp) :: ctemp
           integer(ilp) :: i, ix, iy
           if (n<=0) return
           if (incx==1 .and. incy==1) then
             ! code for both increments equal to 1
              do i = 1,n
                 ctemp = cx(i)
                 cx(i) = cy(i)
                 cy(i) = ctemp
              end do
           else
             ! code for unequal increments or equal increments not equal
               ! to 1
              ix = 1
              iy = 1
              if (incx<0) ix = (-n+1)*incx + 1
              if (incy<0) iy = (-n+1)*incy + 1
              do i = 1,n
                 ctemp = cx(ix)
                 cx(ix) = cy(iy)
                 cy(iy) = ctemp
                 ix = ix + incx
                 iy = iy + incy
              end do
           end if
           return
     end subroutine stdlib_cswap