npm package: @stdlib/complex-float64-base-assert-is-almost-equal
Description: Test whether two double-precision complex 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 whether two double-precision complex floating-point numbers are approximately equal within a specified number of ULPs (units in the last place).

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### isAlmostEqual( z1, z2, maxULP )

Tests whether two double-precision complex 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 Complex128 = require( '@stdlib/complex-float64-ctor' );

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

var out = isAlmostEqual( z1, z2, 0 );
// returns false

out = isAlmostEqual( z1, z2, 1 );
// returns true
```

The function returns `false` if either input value has a `NaN` real or imaginary component.

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

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

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

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

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

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

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

</section>

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<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/complex-float64-base-assert-is-almost-equal' );

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

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

z1 = new Complex128( 0.0, 0.0 );
z2 = new Complex128( -0.0, 0.0 );
console.log( isAlmostEqual( z1, z2, 0 ) );
// => true

z1 = new Complex128( NaN, 0.0 );
z2 = new Complex128( 1.0, 0.0 );
console.log( isAlmostEqual( z1, z2, 1 ) );
// => false
```

</section>

<!-- /.examples -->

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* * *

## 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.

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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