double asin (      double x );
      float asin (       float x );
long double asin ( long double x ); | 
<cmath>  | 
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.
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
/* asin example */
#include <stdio.h>
#include <math.h>
#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.
   | 
See also
| sin |  Compute sine (function) | 
| acos |  Compute arc cosine (function) |