https://github.com/stdlib-js/number-float64-base-signbit
Return a boolean indicating if the sign bit for a double-precision floating-point number is on (true) or off (false).
https://github.com/stdlib-js/number-float64-base-signbit
base bit double float float64 floating-point javascript node node-js nodejs positive sign signbit stdlib type types util utilities utility utils
Last synced: about 2 months ago
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Return a boolean indicating if the sign bit for a double-precision floating-point number is on (true) or off (false).
- Host: GitHub
- URL: https://github.com/stdlib-js/number-float64-base-signbit
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-15T16:54:32.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2025-04-02T09:36:35.000Z (about 2 months ago)
- Last Synced: 2025-04-13T00:28:39.949Z (about 2 months ago)
- Topics: base, bit, double, float, float64, floating-point, javascript, node, node-js, nodejs, positive, sign, signbit, stdlib, type, types, util, utilities, utility, utils
- Language: Python
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 597 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
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README
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# signbit
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Return a boolean indicating if the sign bit for a [double-precision floating-point number][ieee754] is on (true) or off (false).
## Installation
```bash
npm install @stdlib/number-float64-base-signbit
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
## Usage
```javascript
var signbit = require( '@stdlib/number-float64-base-signbit' );
```
#### signbit( x )
Returns a `boolean` indicating if the sign bit for a [double-precision floating-point number][ieee754] is on (`true`) or off (`false`).
```javascript
var bool = signbit( 4.0 );
// returns false
bool = signbit( -9.14e-307 );
// returns true
bool = signbit( 0.0 );
// returns false
bool = signbit( -0.0 );
// returns true
```
## Examples
```javascript
var randu = require( '@stdlib/random-base-randu' );
var signbit = require( '@stdlib/number-float64-base-signbit' );
var sign;
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = ( randu()*100.0 ) - 50.0;
sign = signbit( x );
sign = ( sign ) ? 'true' : 'false';
console.log( 'x: %d. signbit: %s.', x, sign );
}
```
* * *
## C APIs
### Usage
```c
#include "stdlib/number/float64/base/signbit.h"
```
#### stdlib_base_float64_signbit( x )
Returns an integer indicating whether the sign bit for a double-precision floating-point number is on (`1`) or off (`0`).
```c
#include
int8_t out = stdlib_base_float64_signbit( 3.14 );
```
The function accepts the following arguments:
- **x**: `[in] double` input value.
```c
int8_t stdlib_base_float64_signbit( const double x );
```
### Examples
```c
#include "stdlib/number/float64/base/signbit.h"
#include
#include
#include
int main( void ) {
double x[] = { 3.14, -3.14, 0.0, -0.0, 4.0, 1.0, -1.0, 1.0e308, -1.0e308 };
int8_t out;
int i;
for ( i = 0; i < 9; i++ ) {
stdlib_base_float64_signbit( x[ i ], &out );
printf( "%lf => signbit: %" PRId8 "\n", x[ i ], out );
}
}
```
* * *
## See Also
- [`@stdlib/number-float32/base/signbit`][@stdlib/number/float32/base/signbit]: return a boolean indicating if the sign bit for a single-precision floating-point number is on (true) or off (false).
* * *
## 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 © 2016-2025. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/number-float64-base-signbit.svg
[npm-url]: https://npmjs.org/package/@stdlib/number-float64-base-signbit
[test-image]: https://github.com/stdlib-js/number-float64-base-signbit/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/number-float64-base-signbit/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/number-float64-base-signbit/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/number-float64-base-signbit?branch=main
[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[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-float64-base-signbit/tree/deno
[deno-readme]: https://github.com/stdlib-js/number-float64-base-signbit/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/number-float64-base-signbit/tree/umd
[umd-readme]: https://github.com/stdlib-js/number-float64-base-signbit/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/number-float64-base-signbit/tree/esm
[esm-readme]: https://github.com/stdlib-js/number-float64-base-signbit/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/number-float64-base-signbit/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/number-float64-base-signbit/main/LICENSE
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
[@stdlib/number/float32/base/signbit]: https://github.com/stdlib-js/number-float32-base-signbit