LAPACK  3.6.0
LAPACK: Linear Algebra PACKage
izamax.f File Reference

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Functions/Subroutines

integer function izamax (N, ZX, INCX)
 IZAMAX More...
 

Function/Subroutine Documentation

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(.)|
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2015
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 53 of file izamax.f.

53 *
54 * -- Reference BLAS level1 routine (version 3.6.0) --
55 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
56 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
57 * November 2015
58 *
59 * .. Scalar Arguments ..
60  INTEGER incx,n
61 * ..
62 * .. Array Arguments ..
63  COMPLEX*16 zx(*)
64 * ..
65 *
66 * =====================================================================
67 *
68 * .. Local Scalars ..
69  DOUBLE PRECISION dmax
70  INTEGER i,ix
71 * ..
72 * .. External Functions ..
73  DOUBLE PRECISION dcabs1
74  EXTERNAL dcabs1
75 * ..
76  izamax = 0
77  IF (n.LT.1 .OR. incx.LE.0) RETURN
78  izamax = 1
79  IF (n.EQ.1) RETURN
80  IF (incx.EQ.1) THEN
81 *
82 * code for increment equal to 1
83 *
84  dmax = dcabs1(zx(1))
85  DO i = 2,n
86  IF (dcabs1(zx(i)).GT.dmax) THEN
87  izamax = i
88  dmax = dcabs1(zx(i))
89  END IF
90  END DO
91  ELSE
92 *
93 * code for increment not equal to 1
94 *
95  ix = 1
96  dmax = dcabs1(zx(1))
97  ix = ix + incx
98  DO i = 2,n
99  IF (dcabs1(zx(ix)).GT.dmax) THEN
100  izamax = i
101  dmax = dcabs1(zx(ix))
102  END IF
103  ix = ix + incx
104  END DO
105  END IF
106  RETURN
integer function izamax(N, ZX, INCX)
IZAMAX
Definition: izamax.f:53
double precision function dcabs1(Z)
DCABS1
Definition: dcabs1.f:41

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