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
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