LAPACK  3.5.0
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zdotc.f
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1 *> \brief \b ZDOTC
2 *
3 * =========== DOCUMENTATION ===========
4 *
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
7 *
8 * Definition:
9 * ===========
10 *
11 * COMPLEX*16 FUNCTION ZDOTC(N,ZX,INCX,ZY,INCY)
12 *
13 * .. Scalar Arguments ..
14 * INTEGER INCX,INCY,N
15 * ..
16 * .. Array Arguments ..
17 * COMPLEX*16 ZX(*),ZY(*)
18 * ..
19 *
20 *
21 *> \par Purpose:
22 * =============
23 *>
24 *> \verbatim
25 *>
26 *> ZDOTC forms the dot product of a vector.
27 *> \endverbatim
28 *
29 * Authors:
30 * ========
31 *
32 *> \author Univ. of Tennessee
33 *> \author Univ. of California Berkeley
34 *> \author Univ. of Colorado Denver
35 *> \author NAG Ltd.
36 *
37 *> \date November 2011
38 *
39 *> \ingroup complex16_blas_level1
40 *
41 *> \par Further Details:
42 * =====================
43 *>
44 *> \verbatim
45 *>
46 *> jack dongarra, 3/11/78.
47 *> modified 12/3/93, array(1) declarations changed to array(*)
48 *> \endverbatim
49 *>
50 * =====================================================================
51  COMPLEX*16 FUNCTION zdotc(N,ZX,INCX,ZY,INCY)
52 *
53 * -- Reference BLAS level1 routine (version 3.4.0) --
54 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
55 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
56 * November 2011
57 *
58 * .. Scalar Arguments ..
59  INTEGER incx,incy,n
60 * ..
61 * .. Array Arguments ..
62  COMPLEX*16 zx(*),zy(*)
63 * ..
64 *
65 * =====================================================================
66 *
67 * .. Local Scalars ..
68  COMPLEX*16 ztemp
69  INTEGER i,ix,iy
70 * ..
71 * .. Intrinsic Functions ..
72  INTRINSIC dconjg
73 * ..
74  ztemp = (0.0d0,0.0d0)
75  zdotc = (0.0d0,0.0d0)
76  IF (n.LE.0) RETURN
77  IF (incx.EQ.1 .AND. incy.EQ.1) THEN
78 *
79 * code for both increments equal to 1
80 *
81  DO i = 1,n
82  ztemp = ztemp + dconjg(zx(i))*zy(i)
83  END DO
84  ELSE
85 *
86 * code for unequal increments or equal increments
87 * not equal to 1
88 *
89  ix = 1
90  iy = 1
91  IF (incx.LT.0) ix = (-n+1)*incx + 1
92  IF (incy.LT.0) iy = (-n+1)*incy + 1
93  DO i = 1,n
94  ztemp = ztemp + dconjg(zx(ix))*zy(iy)
95  ix = ix + incx
96  iy = iy + incy
97  END DO
98  END IF
99  zdotc = ztemp
100  RETURN
101  END