npm package: @stdlib/math-base-special-floor2
Description: Round a numeric value to the nearest power of two toward negative infinity.
Author: The Stdlib Authors
Latest version: 0.3.1

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# floor2

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> Round a numeric value to the nearest power of two toward negative infinity.

<section class="installation">

## Installation

```bash
npm install @stdlib/math-base-special-floor2
```

</section>

<section class="usage">

## Usage

```javascript
var floor2 = require( '@stdlib/math-base-special-floor2' );
```

#### floor2( x )

Rounds a `numeric` value to the nearest power of two toward negative infinity.

```javascript
var v = floor2( -4.2 );
// returns -8.0

v = floor2( -4.5 );
// returns -8.0

v = floor2( -4.6 );
// returns -8.0

v = floor2( 9.99999 );
// returns 8.0

v = floor2( 9.5 );
// returns 8.0

v = floor2( 13.0 );
// returns 8.0

v = floor2( -13.0 );
// returns -16.0

v = floor2( 0.0 );
// returns 0.0

v = floor2( -0.0 );
// returns -0.0

v = floor2( Infinity );
// returns Infinity

v = floor2( -Infinity );
// returns -Infinity

v = floor2( NaN );
// returns NaN
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var uniform = require( '@stdlib/random-array-uniform' );
var logEachMap = require( '@stdlib/console-log-each-map' );
var floor2 = require( '@stdlib/math-base-special-floor2' );

var opts = {
    'dtype': 'float64'
};
var x = uniform( 100, -50.0, 50.0, opts );

logEachMap( 'x: %0.4f. Rounded: %d.', x, floor2 );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/math/base/special/floor2.h"
```

#### stdlib_base_floor2( x )

Rounds a `numeric` value to the nearest power of two toward negative infinity.

```c
double y = stdlib_base_floor2( -4.2 );
// returns -8.0
```

The function accepts the following arguments:

-   **x**: `[in] double` input value.

```c
double stdlib_base_floor2( const double x );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/math/base/special/floor2.h"
#include <stdio.h>

int main( void ) {
    const double x[] = { 3.14, -3.14, 0.0, 0.0 / 0.0 };

    double y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_floor2( x[ i ] );
        printf( "floor2(%lf) = %lf\n", x[ i ], y );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/math-base/special/ceil2`][@stdlib/math/base/special/ceil2]</span><span class="delimiter">: </span><span class="description">round a numeric value to the nearest power of two toward positive infinity.</span>
-   <span class="package-name">[`@stdlib/math-base/special/floor`][@stdlib/math/base/special/floor]</span><span class="delimiter">: </span><span class="description">round a double-precision floating-point number toward negative infinity.</span>
-   <span class="package-name">[`@stdlib/math-base/special/floor10`][@stdlib/math/base/special/floor10]</span><span class="delimiter">: </span><span class="description">round a numeric value to the nearest power of 10 toward negative infinity.</span>
-   <span class="package-name">[`@stdlib/math-base/special/round2`][@stdlib/math/base/special/round2]</span><span class="delimiter">: </span><span class="description">round a numeric value to the nearest power of two on a linear scale.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<section class="main-repo" >

* * *

## 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 &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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<!-- <related-links> -->

[@stdlib/math/base/special/ceil2]: https://www.npmjs.com/package/@stdlib/math-base-special-ceil2

[@stdlib/math/base/special/floor]: https://www.npmjs.com/package/@stdlib/math-base-special-floor

[@stdlib/math/base/special/floor10]: https://www.npmjs.com/package/@stdlib/math-base-special-floor10

[@stdlib/math/base/special/round2]: https://www.npmjs.com/package/@stdlib/math-base-special-round2

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</section>

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