LinearAlgebra`BLAS`
LinearAlgebra`BLAS`

# IAMAX

IAMAX[x]

gives the position of the element with the maximum absolute value in a vector x.

# Details and Options

• To use IAMAX, you first need to load the BLAS Package using Needs["LinearAlgebra`BLAS`"].
• The following argument must be given:
•  x input expression vector
• For complex vectors x, IAMAX locates the element with the greatest sum of absolute values of the real and imaginary parts.
• If x contains non-numeric elements, then IAMAX[x] always returns \$Failed.
• For duplicate entries the first position found is returned.

# Examples

open allclose all

## Basic Examples(1)

Find the position of the element with the largest absolute value in a vector:

## Scope(4)

A real vector:

A complex vector:

An arbitrary-precision vector:

Vectors with symbolic entries will return \$Failed:

## Properties & Relations(1)

IAMAX[x] is equivalent to Part[Position[Abs[x],Max[Abs[x]]],1,1] for real-valued vectors:

A similar relation is true for complex-valued vectors :

## Possible Issues(2)

If there are multiple elements with the same maximum absolute value, the position of the first one is returned:

If a vector contains a symbol, IAMAX returns \$Failed: