LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
 All Classes Files Functions Variables Typedefs Macros
dzasum.f
Go to the documentation of this file.
1 *> \brief \b DZASUM
2 *
3 * =========== DOCUMENTATION ===========
4 *
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
7 *
8 * Definition:
9 * ===========
10 *
11 * DOUBLE PRECISION FUNCTION DZASUM(N,ZX,INCX)
12 *
13 * .. Scalar Arguments ..
14 * INTEGER INCX,N
15 * ..
16 * .. Array Arguments ..
17 * COMPLEX*16 ZX(*)
18 * ..
19 *
20 *
21 *> \par Purpose:
22 * =============
23 *>
24 *> \verbatim
25 *>
26 *> DZASUM takes the sum of the absolute values.
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 double_blas_level1
40 *
41 *> \par Further Details:
42 * =====================
43 *>
44 *> \verbatim
45 *>
46 *> jack dongarra, 3/11/78.
47 *> modified 3/93 to return if incx .le. 0.
48 *> modified 12/3/93, array(1) declarations changed to array(*)
49 *> \endverbatim
50 *>
51 * =====================================================================
52  DOUBLE PRECISION FUNCTION dzasum(N,ZX,INCX)
53 *
54 * -- Reference BLAS level1 routine (version 3.4.0) --
55 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
56 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
57 * November 2011
58 *
59 * .. Scalar Arguments ..
60  INTEGER incx,n
61 * ..
62 * .. Array Arguments ..
63  COMPLEX*16 zx(*)
64 * ..
65 *
66 * =====================================================================
67 *
68 * .. Local Scalars ..
69  DOUBLE PRECISION stemp
70  INTEGER i,nincx
71 * ..
72 * .. External Functions ..
73  DOUBLE PRECISION dcabs1
74  EXTERNAL dcabs1
75 * ..
76  dzasum = 0.0d0
77  stemp = 0.0d0
78  IF (n.LE.0 .OR. incx.LE.0) RETURN
79  IF (incx.EQ.1) THEN
80 *
81 * code for increment equal to 1
82 *
83  DO i = 1,n
84  stemp = stemp + dcabs1(zx(i))
85  END DO
86  ELSE
87 *
88 * code for increment not equal to 1
89 *
90  nincx = n*incx
91  DO i = 1,nincx,incx
92  stemp = stemp + dcabs1(zx(i))
93  END DO
94  END IF
95  dzasum = stemp
96  RETURN
97  END