caxpy Subroutine

public subroutine caxpy(n, ca, cx, incx, cy, incy)

NAME

 caxpy(3f) -- [BLAS:COMPLEX_BLAS_LEVEL1] CY:=CY+CA*CX (constant times a vector plus a vector)

SYNOPSIS

subroutine caxpy(n,ca,cx,incx,cy,incy)

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

DESCRIPTION

 CAXPY constant times a vector plus a vector.

OPTIONS

N      number of elements in input vector(s)
CA     On entry, CA specifies the scalar alpha.
CX     CX is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
INCX   storage spacing between elements of CX
CY     CY is COMPLEX array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
INCY   storage spacing between elements of CY

AUTHORS

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

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(in) :: ca
complex, intent(in) :: cx(*)
integer, intent(in) :: incx
complex, intent(inout) :: cy(*)
integer, intent(in) :: incy

Contents

Variables

i ix iy

Source Code

caxpy

Variables

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

Source Code

subroutine caxpy(n,ca,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 ..
      complex,intent(in)    :: ca
      integer,intent(in)    :: incx,incy,n
!     ..
!     .. Array Arguments ..
      complex,intent(in)    :: cx(*)
      complex,intent(inout) ::  cy(*)
!     ..
!
!  =====================================================================
!
!     .. Local Scalars ..
      integer :: i,ix,iy
!     ..
!     .. External Functions ..
!     ..
      if (n.le.0) return
      if (scabs1(ca).eq.0.0e+0) return
      if (incx.eq.1 .and. incy.eq.1) then
!
!        code for both increments equal to 1
!
         do i = 1,n
            cy(i) = cy(i) + ca*cx(i)
         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
            cy(iy) = cy(iy) + ca*cx(ix)
            ix = ix + incx
            iy = iy + incy
         enddo
      endif
!
      end subroutine caxpy