atan(), atanf(), atanl()
Compute the arctangent of an angle
Synopsis:
#include <math.h> double atan( double x ); float atanf( float x ); long double atanl( long double x );
Arguments:
- x
- The tangent for which you want to find the angle.
Description:
These functions compute the arctangent (specified in radians) of x.
Returns:
The arctangent, in the range (-π/2, π/2). For finite values of |x| > 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", atan(.5) );
return EXIT_SUCCESS;
}
produces the output:
0.463648
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | No |
| Signal handler | No |
| Thread | Yes |