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# npm

## @stdlib/stats-base-nanmaxabs

0.0.8 • Public • Published

# nanmaxabs

Calculate the maximum absolute value of a strided array, ignoring `NaN` values.

## Installation

`npm install @stdlib/stats-base-nanmaxabs`

## Usage

`var nanmaxabs = require( '@stdlib/stats-base-nanmaxabs' );`

#### nanmaxabs( N, x, stride )

Computes the maximum absolute value of a strided array `x`, ignoring `NaN` values.

```var x = [ 1.0, -2.0, NaN, 2.0 ];
var N = x.length;

var v = nanmaxabs( N, x, 1 );
// returns 2.0```

The function has the following parameters:

The `N` and `stride` parameters determine which elements in `x` are accessed at runtime. For example, to compute the maximum absolute value of every other element in `x`,

```var floor = require( '@stdlib/math-base-special-floor' );

var x = [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0, NaN, NaN ];
var N = floor( x.length / 2 );

var v = nanmaxabs( N, x, 2 );
// returns 4.0```

Note that indexing is relative to the first index. To introduce an offset, use `typed array` views.

```var Float64Array = require( '@stdlib/array-float64' );
var floor = require( '@stdlib/math-base-special-floor' );

var x0 = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, NaN, NaN, 4.0 ] );
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var N = floor( x0.length / 2 );

var v = nanmaxabs( N, x1, 2 );
// returns 4.0```

#### nanmaxabs.ndarray( N, x, stride, offset )

Computes the maximum absolute value of a strided array, ignoring `NaN` values and using alternative indexing semantics.

```var x = [ 1.0, -2.0, NaN, 2.0 ];
var N = x.length;

var v = nanmaxabs.ndarray( N, x, 1, 0 );
// returns 2.0```

The function has the following additional parameters:

• offset: starting index for `x`.

While `typed array` views mandate a view offset based on the underlying `buffer`, the `offset` parameter supports indexing semantics based on a starting index. For example, to calculate the maximum absolute value for every other value in `x` starting from the second value

```var floor = require( '@stdlib/math-base-special-floor' );

var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, NaN, NaN, 2.0, 3.0, 4.0 ];
var N = floor( x.length / 2 );

var v = nanmaxabs.ndarray( N, x, 2, 1 );
// returns 4.0```

## Examples

```var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var Float64Array = require( '@stdlib/array-float64' );
var nanmaxabs = require( '@stdlib/stats-base-nanmaxabs' );

var x;
var i;

x = new Float64Array( 10 );
for ( i = 0; i < x.length; i++ ) {
if ( randu() < 0.2 ) {
x[ i ] = NaN;
} else {
x[ i ] = round( (randu()*100.0) - 50.0 );
}
}
console.log( x );

var v = nanmaxabs( x.length, x, 1 );
console.log( v );```

## Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

### Install

`npm i @stdlib/stats-base-nanmaxabs`

### Repository

github.com/stdlib-js/stats-base-nanmaxabs

stdlib.io

37

0.0.8

Apache-2.0

38 kB

11