1: *> \brief \b IZAMAX
2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: * Definition:
9: * ===========
10: *
11: * INTEGER FUNCTION IZAMAX(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: *> IZAMAX finds the index of the first element having maximum |Re(.)| + |Im(.)|
27: *> \endverbatim
28: *
29: * Arguments:
30: * ==========
31: *
32: *> \param[in] N
33: *> \verbatim
34: *> N is INTEGER
35: *> number of elements in input vector(s)
36: *> \endverbatim
37: *>
38: *> \param[in] ZX
39: *> \verbatim
40: *> ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
41: *> \endverbatim
42: *>
43: *> \param[in] INCX
44: *> \verbatim
45: *> INCX is INTEGER
46: *> storage spacing between elements of SX
47: *> \endverbatim
48: *
49: * Authors:
50: * ========
51: *
52: *> \author Univ. of Tennessee
53: *> \author Univ. of California Berkeley
54: *> \author Univ. of Colorado Denver
55: *> \author NAG Ltd.
56: *
57: *> \date November 2017
58: *
59: *> \ingroup aux_blas
60: *
61: *> \par Further Details:
62: * =====================
63: *>
64: *> \verbatim
65: *>
66: *> jack dongarra, 1/15/85.
67: *> modified 3/93 to return if incx .le. 0.
68: *> modified 12/3/93, array(1) declarations changed to array(*)
69: *> \endverbatim
70: *>
71: * =====================================================================
72: INTEGER FUNCTION IZAMAX(N,ZX,INCX)
73: *
74: * -- Reference BLAS level1 routine (version 3.8.0) --
75: * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
76: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
77: * November 2017
78: *
79: * .. Scalar Arguments ..
80: INTEGER INCX,N
81: * ..
82: * .. Array Arguments ..
83: COMPLEX*16 ZX(*)
84: * ..
85: *
86: * =====================================================================
87: *
88: * .. Local Scalars ..
89: DOUBLE PRECISION DMAX
90: INTEGER I,IX
91: * ..
92: * .. External Functions ..
93: DOUBLE PRECISION DCABS1
94: EXTERNAL DCABS1
95: * ..
96: IZAMAX = 0
97: IF (N.LT.1 .OR. INCX.LE.0) RETURN
98: IZAMAX = 1
99: IF (N.EQ.1) RETURN
100: IF (INCX.EQ.1) THEN
101: *
102: * code for increment equal to 1
103: *
104: DMAX = DCABS1(ZX(1))
105: DO I = 2,N
106: IF (DCABS1(ZX(I)).GT.DMAX) THEN
107: IZAMAX = I
108: DMAX = DCABS1(ZX(I))
109: END IF
110: END DO
111: ELSE
112: *
113: * code for increment not equal to 1
114: *
115: IX = 1
116: DMAX = DCABS1(ZX(1))
117: IX = IX + INCX
118: DO I = 2,N
119: IF (DCABS1(ZX(IX)).GT.DMAX) THEN
120: IZAMAX = I
121: DMAX = DCABS1(ZX(IX))
122: END IF
123: IX = IX + INCX
124: END DO
125: END IF
126: RETURN
127: END
CVSweb interface <joel.bertrand@systella.fr>