npm package: @stdlib/math-base-special-roundnf
Description: Round a single-precision floating-point number to the nearest multiple of 10^n.
Author: The Stdlib Authors
Latest version: 0.1.1

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# roundnf

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> Round a single-precision floating-point number to the nearest multiple of 10^n.

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### roundnf( x, n )

Rounds a single-precision floating-point number to the nearest multiple of `10^n`.

```javascript
// Round a value to 2 decimal places:
var v = roundnf( 3.1415927410125732, -2 );
// returns ~3.14

// If n = 0, `roundnf` behaves like `roundf`:
v = roundnf( 3.1415927410125732, 0 );
// returns 3.0

// Round a value to the nearest thousand:
v = roundnf( 12368.0, 3 );
// returns ~12000.0
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   When operating on [floating-point numbers][ieee754] in bases other than `2`, rounding to specified digits can be **inexact**. For example,

    ```javascript
    var x = 0.2 + 0.1;
    // returns 0.30000000000000004

    // Should round to 0.3...
    var v = roundnf( x, -7 );
    // returns 0.30000001192092896
    ```

-   Ties are rounded toward positive infinity.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

var x = uniform( 100, -50.0, 50.0, {
    'dtype': 'float32'
});

var n = discreteUniform( 100, -5, 0, {
    'dtype': 'int32'
});

logEachMap( 'x: %0.8f. Number of decimals: %d. Rounded: %0.8f.', x, n, roundnf );
```

</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/roundnf.h"
```

#### stdlib_base_roundnf( x, n )

Rounds a single-precision floating-point number to the nearest multiple of `10^n`.

```c
// Round a value to 2 decimal places:
float y = stdlib_base_roundnf( 3.14159f, -2 );
// returns ~3.14f

// If n = 0, `roundnf` behaves like `roundf`:
y = stdlib_base_roundnf( 3.14159f, 0 );
// returns 3.0f
```

The function accepts the following arguments:

-   **x**: `[in] float` input value.
-   **n**: `[in] int32_t` integer power of 10.

```c
float stdlib_base_roundnf( const float x, const int32_t n );
```

</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/roundnf.h"
#include <stdio.h>

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

    float y;
    int i;
    for ( i = 0; i < 4; i++ ) {
        y = stdlib_base_roundnf( x[ i ], -2 );
        printf( "roundnf(%f, -2) = %f\n", x[ i ], y );
    }
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

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<section class="related">

</section>

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<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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

</section>

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[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985

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