zaxpy Subroutine

public subroutine zaxpy(n, za, zx, incx, zy, incy)

NAME

zaxpy(3f) - [BLAS:COMPLEX16_BLAS_LEVEL1] ZY := ZY+ZA*ZX
complex constant times a complex vector plus a complex vector.

SYNOPSIS

 subroutine zaxpy(n,za,zx,incx,zy,incy)

   ! .. Scalar Arguments ..
   complex(kind=real64),intent(in)    :: za
   integer,intent(in)                 :: incx,incy,n
   ! ..
   ! .. Array Arguments ..
   complex(kind=real64),intent(in)    :: zx(*)
   complex(kind=real64),intent(inout) :: zy(*)
   ! ..

DEFINITION

 ZAXPY constant times a vector plus a vector.

     ZY := ZY+ZA*ZX

OPTIONS

N number of elements in input vector(s) ZA On entry, ZA specifies the scalar alpha. ZX ZX is complex(kind=real64) array, dimension ( 1 + ( N - 1 )abs( INCX ) ) INCX storage spacing between elements of ZX ZY ZY is complex(kind=real64) array, dimension ( 1 + ( N - 1 )abs( INCY ) ) INCY storage spacing between elements of ZY

AUTHORS

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

date:November 2017

FURTHER DETAILS

  jack dongarra, 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(kind=real64), intent(in) :: za
complex(kind=real64), intent(in) :: zx(*)
integer, intent(in) :: incx
complex(kind=real64), intent(inout) :: zy(*)
integer, intent(in) :: incy

Contents

Variables

i ix iy

Source Code

zaxpy

Variables

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

Source Code

       subroutine zaxpy(n,za,zx,incx,zy,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(kind=real64),intent(in)    :: za
      integer,intent(in)                 :: incx,incy,n
!     ..
!     .. Array Arguments ..
      complex(kind=real64),intent(in)    :: zx(*)
      complex(kind=real64),intent(inout) :: zy(*)
!     ..
!
!  =====================================================================
!
!     .. Local Scalars ..
      integer i,ix,iy
!     ..
!     .. External Functions ..
!      double precision dcabs1
!      external dcabs1
!     ..
      if (n.le.0) return
      if (dcabs1(za).eq.0.0d0) return
      if (incx.eq.1 .and. incy.eq.1) then
!
!        code for both increments equal to 1
!
         do i = 1,n
            zy(i) = zy(i) + za*zx(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
            zy(iy) = zy(iy) + za*zx(ix)
            ix = ix + incx
            iy = iy + incy
         enddo
      endif
!
      end subroutine zaxpy