# Ramp Function
> Evaluate the [ramp function][ramp-function].
The [ramp function][ramp-function] is defined as
or, alternatively, in terms of the `max` function
## 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
```
## Examples
```javascript
var linspace = require( '@stdlib/array/linspace' );
var rampf = require( '@stdlib/math/base/special/rampf' );
var x = linspace( -10.0, 10.0, 101 );
var i;
for ( i = 0; i < x.length; i++ ) {
console.log( 'R(%d) = %d', x[ i ], rampf( x[ i ] ) );
}
```
* * *
## C APIs
### 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 );
```
### Examples
```c
#include "stdlib/math/base/special/rampf.h"
#include
int main() {
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 );
}
}
```
[ramp-function]: https://en.wikipedia.org/wiki/Ramp_function
