isAlmostEqual

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

Installation

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

Usage

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).

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.

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.

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

Examples

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

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.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.