LAPACK  3.10.0
LAPACK: Linear Algebra PACKage

◆ zaxpy()

subroutine zaxpy ( integer  N,
complex*16  ZA,
complex*16, dimension(*)  ZX,
integer  INCX,
complex*16, dimension(*)  ZY,
integer  INCY 
)

ZAXPY

Purpose:
    ZAXPY constant times a vector plus a vector.
Parameters
[in]N
          N is INTEGER
         number of elements in input vector(s)
[in]ZA
          ZA is COMPLEX*16
           On entry, ZA specifies the scalar alpha.
[in]ZX
          ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
[in]INCX
          INCX is INTEGER
         storage spacing between elements of ZX
[in,out]ZY
          ZY is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCY ) )
[in]INCY
          INCY is INTEGER
         storage spacing between elements of ZY
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
     jack dongarra, 3/11/78.
     modified 12/3/93, array(1) declarations changed to array(*)

Definition at line 87 of file zaxpy.f.

88 *
89 * -- Reference BLAS level1 routine --
90 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
91 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
92 *
93 * .. Scalar Arguments ..
94  COMPLEX*16 ZA
95  INTEGER INCX,INCY,N
96 * ..
97 * .. Array Arguments ..
98  COMPLEX*16 ZX(*),ZY(*)
99 * ..
100 *
101 * =====================================================================
102 *
103 * .. Local Scalars ..
104  INTEGER I,IX,IY
105 * ..
106 * .. External Functions ..
107  DOUBLE PRECISION DCABS1
108  EXTERNAL dcabs1
109 * ..
110  IF (n.LE.0) RETURN
111  IF (dcabs1(za).EQ.0.0d0) RETURN
112  IF (incx.EQ.1 .AND. incy.EQ.1) THEN
113 *
114 * code for both increments equal to 1
115 *
116  DO i = 1,n
117  zy(i) = zy(i) + za*zx(i)
118  END DO
119  ELSE
120 *
121 * code for unequal increments or equal increments
122 * not equal to 1
123 *
124  ix = 1
125  iy = 1
126  IF (incx.LT.0) ix = (-n+1)*incx + 1
127  IF (incy.LT.0) iy = (-n+1)*incy + 1
128  DO i = 1,n
129  zy(iy) = zy(iy) + za*zx(ix)
130  ix = ix + incx
131  iy = iy + incy
132  END DO
133  END IF
134 *
135  RETURN
136 *
137 * End of ZAXPY
138 *
double precision function dcabs1(Z)
DCABS1
Definition: dcabs1.f:47