# C++ Programming/Code/Standard C Library/Functions/asin

## asin

editSyntax |
```
#include <cmath>
double asin( double arg );
``` |

The asin() function returns the arc sine of *arg*, which will be in the range [-pi/2, +pi/2]. *arg* should be between -1 and 1. If *arg* is outside this range, asin() returns NAN and raises a floating-point exception.