LAPACK  3.10.0
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 ZX
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
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 70 of file izamax.f.

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 *
integer function izamax(N, ZX, INCX)
IZAMAX
Definition: izamax.f:71
double precision function dcabs1(Z)
DCABS1
Definition: dcabs1.f:47
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