LAPACK  3.8.0
LAPACK: Linear Algebra PACKage

◆ izamax()

integer function izamax ( integer  N,
complex*16, dimension(*)  ZX,
integer  INCX 
)

IZAMAX

Purpose:
    IZAMAX finds the index of the first element having maximum |Re(.)| + |Im(.)|
Parameters
[in]N
          N is INTEGER
         number of elements in input vector(s)
[in]ZX
          ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
[in]INCX
          INCX is INTEGER
         storage spacing between elements of SX
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2017
Further Details:
     jack dongarra, 1/15/85.
     modified 3/93 to return if incx .le. 0.
     modified 12/3/93, array(1) declarations changed to array(*)

Definition at line 73 of file izamax.f.

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
double precision function dcabs1(Z)
DCABS1
Definition: dcabs1.f:49
integer function izamax(N, ZX, INCX)
IZAMAX
Definition: izamax.f:73
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