https://github.com/stdlib-js/math-base-special-floorb
Round a numeric value to the nearest multiple of b^n toward negative infinity.
https://github.com/stdlib-js/math-base-special-floorb
floor floorb floorn integer javascript math mathematics nearest node node-js nodejs number round stdlib
Last synced: 6 months ago
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Round a numeric value to the nearest multiple of b^n toward negative infinity.
- Host: GitHub
- URL: https://github.com/stdlib-js/math-base-special-floorb
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-15T17:18:45.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2025-04-07T01:19:51.000Z (6 months ago)
- Last Synced: 2025-04-12T22:16:36.276Z (6 months ago)
- Topics: floor, floorb, floorn, integer, javascript, math, mathematics, nearest, node, node-js, nodejs, number, round, stdlib
- Language: Python
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 1.02 MB
- Stars: 2
- 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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# floorb
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Round a numeric value to the nearest multiple of b^n toward negative infinity.
## Installation
```bash
npm install @stdlib/math-base-special-floorb
```
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 floorb = require( '@stdlib/math-base-special-floorb' );
```
#### floorb( x, n, b )
Rounds a `numeric` value to the nearest multiple of `b^n` toward negative infinity.
```javascript
// Round a value to 4 decimal places:
var v = floorb( 3.141592653589793, -4, 10 );
// returns 3.1415
// If n = 0 or b = 1, `floorb` behaves like `floor`:
v = floorb( 3.141592653589793, 0, 2 );
// returns 3.0
// Round a value to the nearest multiple of two toward negative infinity:
v = floorb( 5.0, 1, 2 );
// returns 4.0
```
## Notes
- Due to rounding error in [floating-point numbers][ieee754], rounding may **not** be exact. For example,
```javascript
var x = -0.2 - 0.1;
// returns -0.30000000000000004
// Should round to -0.3...
var v = floorb( x, -16, 10 );
// returns -0.3000000000000001
```
## Examples
```javascript
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var pow = require( '@stdlib/math-base-special-pow' );
var floorb = require( '@stdlib/math-base-special-floorb' );
var x;
var n;
var b;
var v;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
n = round( (randu()*10.0) - 5.0 );
b = round( randu()*10.0 );
v = floorb( x, n, b );
console.log( 'x: %d. %d^%d: %d. Rounded: %d.', x, b, n, pow( b, n ), v );
}
```
### Usage
```c
#include "stdlib/math/base/special/floorb.h"
```
#### stdlib_base_floorb( x, n, b )
Rounds a `numeric` value to the nearest multiple of `b^n` toward negative infinity.
```c
double out = stdlib_base_floorb( 3.141592653589793, -4, 10 );
// returns 3.1415
```
The function accepts the following arguments:
- **x**: `[in] double` input value.
- **n**: `[in] int32_t` power.
- **b**: `[in] int32_t` base.
```c
double stdlib_base_floorb( const double x, const int32_t n, const int32_t b );
```
### Examples
```c
#include "stdlib/math/base/special/floorb.h"
#include
#include
int main( void ) {
const double x[] = { -5.0, -3.89, -2.78, -1.67, -0.56, 0.56, 1.67, 2.78, 3.89, 5.0 };
const int32_t n[] = { -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 };
const int32_t b[] = { 20, 19, 18, 17, 16, 15, 14, 13, 12, 11 };
double v;
int i;
for ( i = 0; i < 10; i++ ) {
v = stdlib_base_floorb( x[ i ], n[ i ], b[ i ] );
printf( "floorb(%lf, %d, %d) = %lf\n", x[ i ], n[ i ], b[ i ], v );
}
}
```
* * *
## See Also
- [`@stdlib/math-base/special/ceilb`][@stdlib/math/base/special/ceilb]: round a numeric value to the nearest multiple of b^n toward positive infinity.
- [`@stdlib/math-base/special/floor`][@stdlib/math/base/special/floor]: round a double-precision floating-point number toward negative infinity.
- [`@stdlib/math-base/special/floorn`][@stdlib/math/base/special/floorn]: round a double-precision floating-point number to the nearest multiple of 10^n toward negative infinity.
- [`@stdlib/math-base/special/roundb`][@stdlib/math/base/special/roundb]: round a numeric value to the nearest multiple of b^n on a linear scale.
* * *
## 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/math-base-special-floorb.svg
[npm-url]: https://npmjs.org/package/@stdlib/math-base-special-floorb
[test-image]: https://github.com/stdlib-js/math-base-special-floorb/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/math-base-special-floorb/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/math-base-special-floorb/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/math-base-special-floorb?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/math-base-special-floorb/tree/deno
[deno-readme]: https://github.com/stdlib-js/math-base-special-floorb/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/math-base-special-floorb/tree/umd
[umd-readme]: https://github.com/stdlib-js/math-base-special-floorb/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/math-base-special-floorb/tree/esm
[esm-readme]: https://github.com/stdlib-js/math-base-special-floorb/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/math-base-special-floorb/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/math-base-special-floorb/main/LICENSE
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
[@stdlib/math/base/special/ceilb]: https://github.com/stdlib-js/math-base-special-ceilb
[@stdlib/math/base/special/floor]: https://github.com/stdlib-js/math-base-special-floor
[@stdlib/math/base/special/floorn]: https://github.com/stdlib-js/math-base-special-floorn
[@stdlib/math/base/special/roundb]: https://github.com/stdlib-js/math-base-special-roundb