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

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/* 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)