cswap Subroutine

public subroutine cswap(n, cx, incx, cy, incy)

NAME

cswap(3f) - [BLAS:COMPLEX_BLAS_LEVEL1] Interchange vectors CX and CY.

SYNOPSIS

 subroutine cswap(n,cx,incx,cy,incy)

   .. Scalar Arguments ..
   integer,intent(in)    :: incx,incy,n
   ..
   .. Array Arguments ..
   complex,intent(inout) :: cx(*),cy(*)
   ..

DEFINITION

CSWAP interchanges two vectors.

OPTIONS

N

       N is INTEGER
      number of elements in input vector(s)

CX

       CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )

INCX

       INCX is INTEGER
      storage spacing between elements of CX

CY

       CY is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCY ) )

INCY

       INCY is INTEGER
      storage spacing between elements of CY

AUTHORS

  • Univ. of Tennessee
  • Univ. of California Berkeley
  • Univ. of Colorado Denver
  • NAG Ltd.

date:November 2017

FURTHER DETAILS

  jack dongarra, linpack, 3/11/78.
  modified 12/3/93, array(1) declarations changed to array(*)

SEE ALSO

Online html documentation available at
http://www.netlib.org/lapack/explore-html/

Arguments

Type IntentOptional Attributes Name
integer, intent(in) :: n
complex, intent(inout) :: cx(*)
integer, intent(in) :: incx
complex, intent(inout) :: cy(*)
integer, intent(in) :: incy

Contents

Variables

Source Code

cswap

Variables

Type Visibility Attributes Name Initial
complex, public :: ctemp
integer, public :: i
integer, public :: ix
integer, public :: iy

Source Code

       subroutine cswap(n,cx,incx,cy,incy)
      implicit none
!
!  -- Reference BLAS level1 routine (version 3.8.0) --
!  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
!  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
!     November 2017
!
!     .. Scalar Arguments ..
      integer,intent(in)    :: incx,incy,n
!     ..
!     .. Array Arguments ..
      complex,intent(inout) :: cx(*),cy(*)
!     ..
!
!  =====================================================================
!
!     .. Local Scalars ..
      complex ctemp
      integer i,ix,iy
!     ..
      if (n.le.0) return
      if (incx.eq.1 .and. incy.eq.1) then
!
!       code for both increments equal to 1
         do i = 1,n
            ctemp = cx(i)
            cx(i) = cy(i)
            cy(i) = ctemp
         enddo
      else
!
!       code for unequal increments or equal increments not equal
!         to 1
!
         ix = 1
         iy = 1
         if (incx.lt.0) ix = (-n+1)*incx + 1
         if (incy.lt.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
         enddo
      endif

      end subroutine cswap