LAPACK  3.10.1
LAPACK: Linear Algebra PACKage
dzasum.f
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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 (|Re(.)| + |Im(.)|)'s of a complex vector and
27 *> returns a double precision result.
28 *> \endverbatim
29 *
30 * Arguments:
31 * ==========
32 *
33 *> \param[in] N
34 *> \verbatim
35 *> N is INTEGER
36 *> number of elements in input vector(s)
37 *> \endverbatim
38 *>
39 *> \param[in,out] ZX
40 *> \verbatim
41 *> ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
42 *> \endverbatim
43 *>
44 *> \param[in] INCX
45 *> \verbatim
46 *> INCX is INTEGER
47 *> storage spacing between elements of ZX
48 *> \endverbatim
49 *
50 * Authors:
51 * ========
52 *
53 *> \author Univ. of Tennessee
54 *> \author Univ. of California Berkeley
55 *> \author Univ. of Colorado Denver
56 *> \author NAG Ltd.
57 *
58 *> \ingroup double_blas_level1
59 *
60 *> \par Further Details:
61 * =====================
62 *>
63 *> \verbatim
64 *>
65 *> jack dongarra, 3/11/78.
66 *> modified 3/93 to return if incx .le. 0.
67 *> modified 12/3/93, array(1) declarations changed to array(*)
68 *> \endverbatim
69 *>
70 * =====================================================================
71  DOUBLE PRECISION FUNCTION dzasum(N,ZX,INCX)
72 *
73 * -- Reference BLAS level1 routine --
74 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
75 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
76 *
77 * .. Scalar Arguments ..
78  INTEGER incx,n
79 * ..
80 * .. Array Arguments ..
81  COMPLEX*16 zx(*)
82 * ..
83 *
84 * =====================================================================
85 *
86 * .. Local Scalars ..
87  DOUBLE PRECISION stemp
88  INTEGER i,nincx
89 * ..
90 * .. External Functions ..
91  DOUBLE PRECISION dcabs1
92  EXTERNAL dcabs1
93 * ..
94  dzasum = 0.0d0
95  stemp = 0.0d0
96  IF (n.LE.0 .OR. incx.LE.0) RETURN
97  IF (incx.EQ.1) THEN
98 *
99 * code for increment equal to 1
100 *
101  DO i = 1,n
102  stemp = stemp + dcabs1(zx(i))
103  END DO
104  ELSE
105 *
106 * code for increment not equal to 1
107 *
108  nincx = n*incx
109  DO i = 1,nincx,incx
110  stemp = stemp + dcabs1(zx(i))
111  END DO
112  END IF
113  dzasum = stemp
114  RETURN
115 *
116 * End of DZASUM
117 *
118  END
double precision function dcabs1(Z)
DCABS1
Definition: dcabs1.f:47
double precision function dzasum(N, ZX, INCX)
DZASUM
Definition: dzasum.f:72