# asin

function
```<cmath> ```
```     double asin (      double x );
float asin (       float x );
long double asin ( long double x );```

Compute arc sine

Returns the principal value of the arc sine of x, expressed in radians.

In trigonometrics, arc sine is the inverse operation of sine.

In C++, this function is overloaded in <valarray> (see valarray asin).

### Parameters

x
Floating point value in the interval [-1,+1].
If the argument is out of this interval, a domain error occurs, setting the global variable errno to the value EDOM.

### Return Value

Arc sine of x, in the interval [-pi/2,+pi/2] radians.

### Portability

In C, only the double version of this function exists with this name.

### Example

 1234567891011121314 ``````/* asin example */ #include #include #define PI 3.14159265 int main () { double param, result; param = 0.5; result = asin (param) * 180.0 / PI; printf ("The arc sine of %lf is %lf degrees\n", param, result ); return 0; }``````

Output:
 ``` The arc sine of 0.500000 is 30.000000 degrees. ```