acos(), acosf(), acosl()
Compute the arccosine of an angle
Synopsis:
#include <math.h> double acos( double x ); float acosf( float x ); long double acosl( long double x );
Arguments:
- x
- The cosine for which you want to find the angle.
Description:
These functions compute the arccosine (specified in radians) of x.
Returns:
The arccosine in the range (0, π). For finite values not in the range [-1,1], these functions return NaN. The return value for +/-Inf is NaN.
If an error occurs, these functions return 0, but this is also a valid
mathematical result.
If you want to check for errors, set
errno
to 0, call the function, and then check errno again.
These functions don't change errno if no errors occurred.
Examples:
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
int main( void )
{
printf( "%f\n", acos(.5) );
return EXIT_SUCCESS;
}
produces the output:
1.047197
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | No |
| Signal handler | No |
| Thread | Yes |