ulp (epsilon function)

> Compute the ULP
of a given IEEE-754 64-bit number: eps(x) (alias: ulp(x)).

> Get the closest representable number that comes before/after it on the float64
number line: nextFloat(x), prevFloat(x).

Install

``sh
npm install @lvlte/ulp
`

Usage

$3

`js
// ESM
import { eps, nextFloat, prevFloat } from '@lvlte/ulp';
`
`js
// CJS
const { eps, nextFloat, prevFloat } = require('@lvlte/ulp');
`

$3


`js
console.log( eps() ); // 2.220446049250313e-16
console.log( eps() === eps(1) ); // true
console.log( eps() === Number.EPSILON ); // true

console.log( eps(Number.MAX_SAFE_INTEGER) ); // 1
console.log( eps(Number.MAX_SAFE_INTEGER + 1) ); // 2

console.log( eps(0) ); // 5e-324
console.log( eps(0) === Number.MIN_VALUE ); // true

console.log( eps(Infinity) ); // NaN
`

$3


`js
console.log( nextFloat(0) ); // 5e-324
console.log( nextFloat(0) === Number.MIN_VALUE ); // true

console.log( nextFloat(1) ); // 1.0000000000000002
console.log( nextFloat(1) === 1 + eps(1) ); // true

console.log( nextFloat(Number.MAX_SAFE_INTEGER) ); // 9007199254740992
console.log( nextFloat(9007199254740992) ); // 9007199254740994
console.log( nextFloat(Number.MAX_VALUE) ); // Infinity

console.log( prevFloat(0) ); // -5e-324
console.log( prevFloat(1) ); // 0.9999999999999999
console.log( prevFloat(9007199254740992) ); // 9007199254740991
console.log( prevFloat(Infinity) ); // 1.7976931348623157e+308
``

Use case

- Use the proper tolerance to check whether two floating-point numbers should be considered equal.
- Use the proper tolerance to approximate a floating-point number as a rational number.