Arc cosine
[Classification]
Mathematical library
[Syntax]
#include <math.h>
float __far acosf(float x);
[Return value]
Returns the arc cosine of x. The returned value is in radian and in a range of [0, ].
If x is not between [-1, 1], acosf returns a Not-a-Number (NaN) and sets macro EDOM to global variable errno.
[Description]
This function calculates the arc cosine of x. Specify x as, -1<= x <= 1.