# erfc
> [Complementary error function][complementary-error-function].
The [complementary error function][complementary-error-function] is defined as
The [complementary error function][complementary-error-function] can also be expressed using Craig's formula
## Usage
```javascript
var erfc = require( '@stdlib/math/base/special/erfc' );
```
#### erfc( x )
Evaluates the [complementary error function][complementary-error-function].
```javascript
var y = erfc( 2.0 );
// returns ~0.0047
y = erfc( -1.0 );
// returns ~1.8427
y = erfc( Infinity );
// returns 0.0
y = erfc( -Infinity );
// returns 2.0
```
If provided `NaN`, the function returns `NaN`.
```javascript
var y = erfc( NaN );
// returns NaN
```
## Examples
```javascript
var linspace = require( '@stdlib/array/linspace' );
var erfc = require( '@stdlib/math/base/special/erfc' );
var x = linspace( -10.0, 10.0, 100 );
var y;
var i;
for ( i = 0; i < x.length; i++ ) {
y = erfc( x[ i ] );
console.log( 'x: %d, erfc(x): %d', x[ i ], y );
}
```
[complementary-error-function]: https://en.wikipedia.org/wiki/Error_function
