npm package: @stdlib/assert-is-almost-equal
Description: Test if two arguments are approximately equal within a specified number of ULPs (units in the last place).
Author: The Stdlib Authors
Latest version: 0.1.1

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</details>

# isAlmostEqual

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Test if two arguments are approximately equal within a specified number of ULPs (units in the last place).

<section class="installation">

## Installation

```bash
npm install @stdlib/assert-is-almost-equal
```

</section>

<section class="usage">

## Usage

```javascript
var isAlmostEqual = require( '@stdlib/assert-is-almost-equal' );
```

#### isAlmostEqual( a, b, maxULP )

Tests if two arguments are approximately equal within a specified number of ULPs (units in the last place).

```javascript
var EPS = require( '@stdlib/constants-float64-eps' );

var bool = isAlmostEqual( 1.0, 1.0+EPS, 1 );
// returns true

bool = isAlmostEqual( '', '', 0 );
// returns true

bool = isAlmostEqual( {}, {}, 1 );
// returns false
```

The function returns `false` if either input value is `NaN` or, in the case of [complex numbers][@stdlib/complex], if either the real or imaginary component is `NaN`.

```javascript
var Complex128 = require( '@stdlib/complex-float64-ctor' );

var bool = isAlmostEqual( NaN, 1.0, 1 );
// returns false

bool = isAlmostEqual( NaN, NaN, 1 );
// returns false

var z1 = new Complex128( NaN, 3.0 );
var z2 = new Complex128( 1.0, 3.0 );

bool = isAlmostEqual( z1, z2, 1 );
// returns false

z1 = new Complex128( NaN, NaN );
z2 = new Complex128( NaN, NaN );

bool = isAlmostEqual( z1, z2, 1 );
// returns false
```

The function does not distinguish between `-0` and `+0`, treating them as equal.

```javascript
var Complex128 = require( '@stdlib/complex-float64-ctor' );

var bool = isAlmostEqual( 0.0, -0.0, 0 );
// returns true

var z1 = new Complex128( 0.0, 0.0 );
var z2 = new Complex128( -0.0, -0.0 );

bool = isAlmostEqual( z1, z2, 0 );
// returns true
```

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var EPS = require( '@stdlib/constants-float64-eps' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var isAlmostEqual = require( '@stdlib/assert-is-almost-equal' );

console.log( isAlmostEqual( true, true, 0 ) );
// => true

console.log( isAlmostEqual( true, false, 1 ) );
// => false

console.log( isAlmostEqual( 'beep', 'beep', 1 ) );
// => true

console.log( isAlmostEqual( 1.0, 1.0+EPS, 1 ) );
// => true

console.log( isAlmostEqual( null, null, 0 ) );
// => true

console.log( isAlmostEqual( 0.0, -0.0, 0 ) );
// => true

console.log( isAlmostEqual( NaN, NaN, 1 ) );
// => false

var z1 = new Complex128( 1.0, 3.0+EPS );
var z2 = new Complex128( 1.0+EPS, 3.0 );
console.log( isAlmostEqual( z1, z2, 1 ) );
// => true

console.log( isAlmostEqual( {}, {}, 1 ) );
// => false

console.log( isAlmostEqual( [], [], 1 ) );
// => false

console.log( isAlmostEqual( isAlmostEqual, isAlmostEqual, 0 ) );
// => true
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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<section class="links">

[npm-image]: http://img.shields.io/npm/v/@stdlib/assert-is-almost-equal.svg
[npm-url]: https://npmjs.org/package/@stdlib/assert-is-almost-equal

[test-image]: https://github.com/stdlib-js/assert-is-almost-equal/actions/workflows/test.yml/badge.svg?branch=v0.1.1
[test-url]: https://github.com/stdlib-js/assert-is-almost-equal/actions/workflows/test.yml?query=branch:v0.1.1

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/assert-is-almost-equal/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/assert-is-almost-equal?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/assert-is-almost-equal/tree/deno
[deno-readme]: https://github.com/stdlib-js/assert-is-almost-equal/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/assert-is-almost-equal/tree/umd
[umd-readme]: https://github.com/stdlib-js/assert-is-almost-equal/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/assert-is-almost-equal/tree/esm
[esm-readme]: https://github.com/stdlib-js/assert-is-almost-equal/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/assert-is-almost-equal/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-almost-equal/main/LICENSE

[@stdlib/complex]: https://www.npmjs.com/package/@stdlib/complex

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</section>

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