---
name: "imax1"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/imax1"
---

# imax1(3)

imax1: argmax\_i \| x\_i \| (in LAPACK)

## NAME

imax1 - imax1: argmax\_i \| x\_i \| (in LAPACK)

## SYNOPSIS

### Functions

integer function **icmax1** (n, cx, incx)\
 **ICMAX1** finds the index of the first vector element of maximum absolute value.  integer function **izmax1** (n, zx, incx)\
 **IZMAX1** finds the index of the first vector element of maximum absolute value.

## Detailed Description

## Function Documentation

### integer function icmax1 (integer n, complex, dimension(\*) cx, integer incx)

**ICMAX1** finds the index of the first vector element of maximum absolute value.

**Purpose:**

```
!>
!> ICMAX1 finds the index of the first vector element of maximum absolute value.
!>
!> Based on ICAMAX from Level 1 BLAS.
!> The change is to use the 'genuine' absolute value.
!>
```

**Parameters**

*N*

```
!>          N is INTEGER
!>          The number of elements in the vector CX.
!>
```

*CX*

```
!>          CX is COMPLEX array, dimension (N)
!>          The vector CX. The ICMAX1 function returns the index of its first
!>          element of maximum absolute value.
!>
```

*INCX*

```
!>          INCX is INTEGER
!>          The spacing between successive values of CX.  INCX >= 1.
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Contributors:**

Nick Higham for use with CLACON.

Definition at line **80** of file **icmax1.f**.

### integer function izmax1 (integer n, complex\*16, dimension(\*) zx, integer incx)

**IZMAX1** finds the index of the first vector element of maximum absolute value.

**Purpose:**

```
!>
!> IZMAX1 finds the index of the first vector element of maximum absolute value.
!>
!> Based on IZAMAX from Level 1 BLAS.
!> The change is to use the 'genuine' absolute value.
!>
```

**Parameters**

*N*

```
!>          N is INTEGER
!>          The number of elements in the vector ZX.
!>
```

*ZX*

```
!>          ZX is COMPLEX*16 array, dimension (N)
!>          The vector ZX. The IZMAX1 function returns the index of its first
!>          element of maximum absolute value.
!>
```

*INCX*

```
!>          INCX is INTEGER
!>          The spacing between successive values of ZX.  INCX >= 1.
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Contributors:**

Nick Higham for use with ZLACON.

Definition at line **80** of file **izmax1.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.