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# Ramp Function

> Evaluate the [ramp function][ramp-function].

<section class="intro">

The [ramp function][ramp-function] is defined as

<!-- <equation class="equation" label="eq:ramp_function" align="center" raw="R(x) = \begin{cases} x & \textrm{if}\ x \geq 0 \\ 0 & \textrm{if}\ x \lt 0\end{cases}" alt="Ramp function."> -->

<div class="equation" align="center" data-raw-text="R(x) = \begin{cases} x &amp; \textrm{if}\ x \geq 0 \\ 0 &amp; \textrm{if}\ x \lt 0\end{cases}" data-equation="eq:ramp_function">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@3aca1e2faee6c79270455562ed28fda2e5e31c4c/lib/node_modules/@stdlib/math/base/special/rampf/docs/img/equation_ramp_function.svg" alt="Ramp function.">
    <br>
</div> -->

<!-- </equation> -->

or, alternatively, in terms of the `max` function

<!-- <equation class="equation" label="eq:ramp_function_alternative_defn" align="center" raw="R(x) = \operatorname{max}( x, 0 )" alt="Ramp function alternative definition."> -->

<!-- <div class="equation" align="center" data-raw-text="R(x) = \operatorname{max}( x, 0 )" data-equation="eq:ramp_function_alternative_defn">
    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@3aca1e2faee6c79270455562ed28fda2e5e31c4c/lib/node_modules/@stdlib/math/base/special/rampf/docs/img/equation_ramp_function_alternative_defn.svg" alt="Ramp function alternative definition.">
    <br>
</div>

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="usage">

## Usage

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

#### rampf( x )

Evaluates the [ramp function][ramp-function].

```javascript
var v = rampf( 3.14 );
// returns 3.14

v = rampf( -3.14 );
// returns 0.0

v = rampf( 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 rampf = require( '@stdlib/math/base/special/rampf' );

var opts = {
    'dtype': 'float32'
};
var x = uniform( 101, -10.0, 10.0, opts );

logEachMap( 'R(%0.4f) = %0.4f', x, rampf );
```

</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/rampf.h"
```

#### stdlib_base_rampf( x )

Evaluates the ramp function (single-precision).

```c
float y = stdlib_base_rampf( 3.0f );
// returns 3.0f
```

The function accepts the following arguments:

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

```c
float stdlib_base_rampf( const float 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/rampf.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_rampf( x[ i ] );
        printf( "R(%f) = %f\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/ramp`][@stdlib/math/base/special/ramp]</span><span class="delimiter">: </span><span class="description">evaluate the ramp function.</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="links">

[ramp-function]: https://en.wikipedia.org/wiki/Ramp_function

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

[@stdlib/math/base/special/ramp]: https://github.com/stdlib-js/math/tree/main/base/special/ramp

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

</section>

<!-- /.links -->
