https://github.com/stdlib-js/number-float64-base-to-int64-bytes
Convert an integer-valued double-precision floating-point number to a signed 64-bit integer byte array according to host byte order.
https://github.com/stdlib-js/number-float64-base-to-int64-bytes
base cast convert dbl double float64 int int64 integer javascript node node-js nodejs stdlib type types util utilities utility utils
Last synced: 4 months ago
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Convert an integer-valued double-precision floating-point number to a signed 64-bit integer byte array according to host byte order.
- Host: GitHub
- URL: https://github.com/stdlib-js/number-float64-base-to-int64-bytes
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-15T18:48:14.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2025-02-24T03:18:19.000Z (12 months ago)
- Last Synced: 2025-10-05T22:43:31.460Z (4 months ago)
- Topics: base, cast, convert, dbl, double, float64, int, int64, integer, javascript, node, node-js, nodejs, stdlib, type, types, util, utilities, utility, utils
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 606 KB
- Stars: 1
- Watchers: 2
- 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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# toInt64Bytes
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Convert an integer-valued [double-precision floating-point number][ieee754] to a signed 64-bit integer byte array according to host byte order (endianness).
## Installation
```bash
npm install @stdlib/number-float64-base-to-int64-bytes
```
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 float64ToInt64Bytes = require( '@stdlib/number-float64-base-to-int64-bytes' );
```
#### float64ToInt64Bytes( x )
Converts an integer-valued [double-precision floating-point number][ieee754] to a signed 64-bit integer byte array according to host byte order (endianness).
```javascript
var out = float64ToInt64Bytes( 4294967297.0 );
// returns
```
#### float64ToInt64Bytes.assign( x, out, stride, offset )
Converts an integer-valued [double-precision floating-point number][ieee754] to a signed 64-bit integer byte array according to host byte order (endianness) and assigns results to a provided output array.
```javascript
var Uint8Array = require( '@stdlib/array-uint8' );
var out = new Uint8Array( 16 );
var y = float64ToInt64Bytes.assign( 4294967297.0, out, 2, 1 );
// returns
var bool = ( y === out );
// returns true
```
## Notes
- The functions assume that the input value is less than the maximum safe [double-precision floating-point][ieee754] integer plus one (i.e., `2**53`).
## Examples
```javascript
var toBinaryStringUint8 = require( '@stdlib/number-uint8-base-to-binary-string' );
var float64ToInt64Bytes = require( '@stdlib/number-float64-base-to-int64-bytes' );
var bytes;
var str;
var sgn;
var x;
var i;
var j;
str = [ '', '', '', '', '', '', '', '', '' ];
x = 1;
for ( i = 0; i < 54; i++ ) {
sgn = ( i&1 ) ? -1 : 1;
bytes = float64ToInt64Bytes( x*sgn );
for ( j = 0; j < bytes.length; j++ ) {
str[ j ] = toBinaryStringUint8( bytes[ j ] );
}
console.log( '%s2**%d => %s', ( sgn < 0 ) ? '-' : '+', i, str.join( ' ' ) );
x *= 2;
}
```
* * *
## See Also
- [`@stdlib/number-float64/base/to-int32`][@stdlib/number/float64/base/to-int32]: convert a double-precision floating-point number to a signed 32-bit integer.
* * *
## 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-to-int64-bytes.svg
[npm-url]: https://npmjs.org/package/@stdlib/number-float64-base-to-int64-bytes
[test-image]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/number-float64-base-to-int64-bytes/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/number-float64-base-to-int64-bytes?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-to-int64-bytes/tree/deno
[deno-readme]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/tree/umd
[umd-readme]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/tree/esm
[esm-readme]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/number-float64-base-to-int64-bytes/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/number-float64-base-to-int64-bytes/main/LICENSE
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
[@stdlib/number/float64/base/to-int32]: https://github.com/stdlib-js/number-float64-base-to-int32