# deg2rad
> Convert an angle from degrees to radians.
## Usage
```javascript
var deg2rad = require( '@stdlib/math/base/special/deg2rad' );
```
#### deg2rad( x )
Converts an angle from degrees to radians.
```javascript
var r = deg2rad( 90.0 );
// returns ~1.571
r = deg2rad( -45.0 );
// returns ~-0.785
r = deg2rad( NaN );
// returns NaN
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var deg2rad = require( '@stdlib/math/base/special/deg2rad' );
var d;
var r;
var i;
for ( i = 0; i < 100; i++ ) {
d = (randu()*720.0) - 360.0;
r = deg2rad( d );
console.log( 'degrees: %d => radians: %d', d, r );
}
```
* * *
## C APIs
### Usage
```c
#include "stdlib/math/base/special/deg2rad.h"
```
#### stdlib_base_deg2rad( x )
Converts an angle from degrees to radians.
```c
double y = stdlib_base_deg2rad( 90.0 );
// returns ~1.571
```
The function accepts the following arguments:
- **x**: `[in] double` input value.
```c
double stdlib_base_deg2rad( const double x );
```
### Examples
```c
#include "stdlib/math/base/special/deg2rad.h"
#include
int main() {
double x[] = { 45.0, 90.0, 0.0, 0.0/0.0 };
double y;
int i;
for ( i = 0; i < 4; i++ ) {
y = stdlib_base_deg2rad( x[ i ] );
printf( "deg2rad(%lf) = %lf\n", x[ i ], y );
}
}
```