LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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izamax.f
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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 ZX
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*> \ingroup iamax
58*
59*> \par Further Details:
60* =====================
61*>
62*> \verbatim
63*>
64*> jack dongarra, 1/15/85.
65*> modified 3/93 to return if incx .le. 0.
66*> modified 12/3/93, array(1) declarations changed to array(*)
67*> \endverbatim
68*>
69* =====================================================================
70 INTEGER FUNCTION izamax(N,ZX,INCX)
71*
72* -- Reference BLAS level1 routine --
73* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
74* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
75*
76* .. Scalar Arguments ..
77 INTEGER incx,n
78* ..
79* .. Array Arguments ..
80 COMPLEX*16 zx(*)
81* ..
82*
83* =====================================================================
84*
85* .. Local Scalars ..
86 DOUBLE PRECISION dmax
87 INTEGER i,ix
88* ..
89* .. External Functions ..
90 DOUBLE PRECISION dcabs1
91 EXTERNAL dcabs1
92* ..
93 izamax = 0
94 IF (n.LT.1 .OR. incx.LE.0) RETURN
95 izamax = 1
96 IF (n.EQ.1) RETURN
97 IF (incx.EQ.1) THEN
98*
99* code for increment equal to 1
100*
101 dmax = dcabs1(zx(1))
102 DO i = 2,n
103 IF (dcabs1(zx(i)).GT.dmax) THEN
104 izamax = i
105 dmax = dcabs1(zx(i))
106 END IF
107 END DO
108 ELSE
109*
110* code for increment not equal to 1
111*
112 ix = 1
113 dmax = dcabs1(zx(1))
114 ix = ix + incx
115 DO i = 2,n
116 IF (dcabs1(zx(ix)).GT.dmax) THEN
117 izamax = i
118 dmax = dcabs1(zx(ix))
119 END IF
120 ix = ix + incx
121 END DO
122 END IF
123 RETURN
124*
125* End of IZAMAX
126*
127 END
double precision function dcabs1(z)
DCABS1
Definition dcabs1.f:47
integer function izamax(n, zx, incx)
IZAMAX
Definition izamax.f:71