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 single 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: *> \date November 2017
59: *
60: *> \ingroup double_blas_level1
61: *
62: *> \par Further Details:
63: * =====================
64: *>
65: *> \verbatim
66: *>
67: *> jack dongarra, 3/11/78.
68: *> modified 3/93 to return if incx .le. 0.
69: *> modified 12/3/93, array(1) declarations changed to array(*)
70: *> \endverbatim
71: *>
72: * =====================================================================
73: DOUBLE PRECISION FUNCTION DZASUM(N,ZX,INCX)
74: *
75: * -- Reference BLAS level1 routine (version 3.8.0) --
76: * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
77: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
78: * November 2017
79: *
80: * .. Scalar Arguments ..
81: INTEGER INCX,N
82: * ..
83: * .. Array Arguments ..
84: COMPLEX*16 ZX(*)
85: * ..
86: *
87: * =====================================================================
88: *
89: * .. Local Scalars ..
90: DOUBLE PRECISION STEMP
91: INTEGER I,NINCX
92: * ..
93: * .. External Functions ..
94: DOUBLE PRECISION DCABS1
95: EXTERNAL DCABS1
96: * ..
97: DZASUM = 0.0d0
98: STEMP = 0.0d0
99: IF (N.LE.0 .OR. INCX.LE.0) RETURN
100: IF (INCX.EQ.1) THEN
101: *
102: * code for increment equal to 1
103: *
104: DO I = 1,N
105: STEMP = STEMP + DCABS1(ZX(I))
106: END DO
107: ELSE
108: *
109: * code for increment not equal to 1
110: *
111: NINCX = N*INCX
112: DO I = 1,NINCX,INCX
113: STEMP = STEMP + DCABS1(ZX(I))
114: END DO
115: END IF
116: DZASUM = STEMP
117: RETURN
118: END
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