# Truncate
> Round a double-precision floating-point number toward zero.
## Usage
```javascript
var trunc = require( '@stdlib/math/base/special/trunc' );
```
#### trunc( x )
Rounds a double-precision floating-point number toward zero.
```javascript
var v = trunc( -4.2 );
// returns -4.0
v = trunc( 9.99999 );
// returns 9.0
v = trunc( 0.0 );
// returns 0.0
v = trunc( -0.0 );
// returns -0.0
v = trunc( NaN );
// returns NaN
v = trunc( Infinity );
// returns Infinity
v = trunc( -Infinity );
// returns -Infinity
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var trunc = require( '@stdlib/math/base/special/trunc' );
var x;
var i;
for ( i = 0; i < 100; i++ ) {
x = (randu()*100.0) - 50.0;
console.log( 'trunc(%d) = %d', x, trunc( x ) );
}
```
* * *
## C APIs
### Usage
```c
#include "stdlib/math/base/special/trunc.h"
```
#### stdlib_base_trunc( x )
Rounds a double-precision floating-point number toward zero.
```c
double y = stdlib_base_trunc( 3.14 );
// returns 3.0
```
The function accepts the following arguments:
- **x**: `[in] double` input value.
```c
double stdlib_base_trunc( const double x );
```
### Examples
```c
#include "stdlib/math/base/special/trunc.h"
#include
int main() {
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_trunc( x[ i ] );
printf( "trunc(%lf) = %lf\n", x[ i ], y );
}
}
```