 LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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## ◆ idamax()

 integer function idamax ( integer N, double precision, dimension(*) DX, integer INCX )

IDAMAX

Purpose:
`    IDAMAX finds the index of the first element having maximum absolute value.`
Parameters
 [in] N ``` N is INTEGER number of elements in input vector(s)``` [in] DX ` DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) )` [in] INCX ``` INCX is INTEGER storage spacing between elements of DX```
Further Details:
```     jack dongarra, linpack, 3/11/78.
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 idamax.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 DOUBLE PRECISION DX(*)
81* ..
82*
83* =====================================================================
84*
85* .. Local Scalars ..
86 DOUBLE PRECISION DMAX
87 INTEGER I,IX
88* ..
89* .. Intrinsic Functions ..
90 INTRINSIC dabs
91* ..
92 idamax = 0
93 IF (n.LT.1 .OR. incx.LE.0) RETURN
94 idamax = 1
95 IF (n.EQ.1) RETURN
96 IF (incx.EQ.1) THEN
97*
98* code for increment equal to 1
99*
100 dmax = dabs(dx(1))
101 DO i = 2,n
102 IF (dabs(dx(i)).GT.dmax) THEN
103 idamax = i
104 dmax = dabs(dx(i))
105 END IF
106 END DO
107 ELSE
108*
109* code for increment not equal to 1
110*
111 ix = 1
112 dmax = dabs(dx(1))
113 ix = ix + incx
114 DO i = 2,n
115 IF (dabs(dx(ix)).GT.dmax) THEN
116 idamax = i
117 dmax = dabs(dx(ix))
118 END IF
119 ix = ix + incx
120 END DO
121 END IF
122 RETURN
123*
124* End of IDAMAX
125*
integer function idamax(N, DX, INCX)
IDAMAX
Definition: idamax.f:71
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