Arc cosine

[Classification]

Mathematical library

[Syntax]

#include <mathf.h>

float acosf(float x);

[Return value]

Returns the arc cosine of x. The returned value is in radian and in a range of 0 to π.

If x is not between -1 and 1, a NaN is returned, and macro EDOM is set to global variable errno.

[Description]

This function calculates the arc cosine of x. Specify x as, -1<= x <= 1.