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: * Authors:
31: * ========
32: *
33: *> \author Univ. of Tennessee
34: *> \author Univ. of California Berkeley
35: *> \author Univ. of Colorado Denver
36: *> \author NAG Ltd.
37: *
38: *> \date November 2015
39: *
40: *> \ingroup double_blas_level1
41: *
42: *> \par Further Details:
43: * =====================
44: *>
45: *> \verbatim
46: *>
47: *> jack dongarra, 3/11/78.
48: *> modified 3/93 to return if incx .le. 0.
49: *> modified 12/3/93, array(1) declarations changed to array(*)
50: *> \endverbatim
51: *>
52: * =====================================================================
53: DOUBLE PRECISION FUNCTION DZASUM(N,ZX,INCX)
54: *
55: * -- Reference BLAS level1 routine (version 3.6.0) --
56: * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
57: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
58: * November 2015
59: *
60: * .. Scalar Arguments ..
61: INTEGER INCX,N
62: * ..
63: * .. Array Arguments ..
64: COMPLEX*16 ZX(*)
65: * ..
66: *
67: * =====================================================================
68: *
69: * .. Local Scalars ..
70: DOUBLE PRECISION STEMP
71: INTEGER I,NINCX
72: * ..
73: * .. External Functions ..
74: DOUBLE PRECISION DCABS1
75: EXTERNAL DCABS1
76: * ..
77: DZASUM = 0.0d0
78: STEMP = 0.0d0
79: IF (N.LE.0 .OR. INCX.LE.0) RETURN
80: IF (INCX.EQ.1) THEN
81: *
82: * code for increment equal to 1
83: *
84: DO I = 1,N
85: STEMP = STEMP + DCABS1(ZX(I))
86: END DO
87: ELSE
88: *
89: * code for increment not equal to 1
90: *
91: NINCX = N*INCX
92: DO I = 1,NINCX,INCX
93: STEMP = STEMP + DCABS1(ZX(I))
94: END DO
95: END IF
96: DZASUM = STEMP
97: RETURN
98: END
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