npm package: @stdlib/number-float64-base-assert-is-almost-equal
Description: Test if two double-precision floating-point numbers are approximately equal within a specified number of ULPs (units in the last place).
Author: The Stdlib Authors
Latest version: 0.0.1

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# isAlmostEqual

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> Test if two double-precision floating-point numbers are approximately equal within a specified number of ULPs (units in the last place).

<section class="installation">

## Installation

```bash
npm install @stdlib/number-float64-base-assert-is-almost-equal
```

</section>

<section class="usage">

## Usage

```javascript
var isAlmostEqual = require( '@stdlib/number-float64-base-assert-is-almost-equal' );
```

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

Tests if two double-precision floating-point numbers 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( 1.0, 1.0+EPS, 0 );
// returns false
```

The function returns `false` if either input value is `NaN`.

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

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

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

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

```javascript
var bool = isAlmostEqual( 0.0, -0.0, 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 isAlmostEqual = require( '@stdlib/number-float64-base-assert-is-almost-equal' );

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

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

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

bool = isAlmostEqual( 1.0, 1.0+EPS, 0 );
console.log( bool );
// => false

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

bool = isAlmostEqual( 1.0, NaN, 1 );
console.log( bool );
// => false

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

</section>

<!-- /.examples -->

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<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>

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