Compute the number of representable single-precision floating-point values that separate two single-precision floating-point numbers along the real number line.
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> Compute the number of representable [single-precision][single-precision] floating-point values that separate two [single-precision][single-precision] floating-point numbers along the real number line.
``bash`
npm install @stdlib/number-float32-base-ulp-difference
`javascript`
var ulpdiff = require( '@stdlib/number-float32-base-ulp-difference' );
#### ulpdiff( x, y )
Computes the number of representable [single-precision][single-precision] floating-point values that separate two [single-precision][single-precision] floating-point numbers along the real number line.
`javascript
var EPS = require( '@stdlib/constants-float32-eps' );
var d = ulpdiff( 1.0, 1.0+EPS );
// returns 1.0
d = ulpdiff( 1.0+EPS, 1.0 );
// returns 1.0
d = ulpdiff( 1.0, 1.0+EPS+EPS );
// returns 2.0
d = ulpdiff( 1.0, NaN );
// returns NaN
d = ulpdiff( NaN, 1.0 );
// returns NaN
d = ulpdiff( NaN, NaN );
// returns NaN
`
- Adjacent [single-precision][single-precision] floating-point numbers differ by 1 [ulp][ulp] (unit in the last place).0
- Signed zeros differ only in the sign bit but are considered numerically equal, and thus their ULP difference is .
`javascript
var EPS = require( '@stdlib/constants-float32-eps' );
var SMALLEST_SUBNORMAL = require( '@stdlib/constants-float32-smallest-subnormal' );
var ulpdiff = require( '@stdlib/number-float32-base-ulp-difference' );
var d = ulpdiff( 1.0, 1.0+EPS );
console.log( d );
// => 1.0
d = ulpdiff( 5.8364e-31, 5.8367e-31 );
console.log( d );
// => 638.0
d = ulpdiff( 0.0, SMALLEST_SUBNORMAL );
console.log( d );
// => 1.0
d = ulpdiff( 0.0, -0.0 );
console.log( d );
// => 0.0
d = ulpdiff( SMALLEST_SUBNORMAL, -SMALLEST_SUBNORMAL );
console.log( d );
// => 2.0
`
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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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/number-float32-base-ulp-difference/tree/deno
[deno-readme]: https://github.com/stdlib-js/number-float32-base-ulp-difference/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/number-float32-base-ulp-difference/tree/umd
[umd-readme]: https://github.com/stdlib-js/number-float32-base-ulp-difference/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/number-float32-base-ulp-difference/tree/esm
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[single-precision]: https://en.wikipedia.org/wiki/Single-precision_floating-point_format
[ulp]: https://en.wikipedia.org/wiki/Unit_in_the_last_place