ACOS

acos ? arc cosine function

#include <math.h>

double acos(double x);

The acos() function calculates the arc cosine of x; that is the value whose cosine is x. If x falls outside the range ?1 to 1, acos() fails and errno is set.

The acos() function returns the arc cosine in radians and the value is mathematically defined to be between 0 and PI (inclusive).

EDOM

x is out of range.

SVID 3, POSIX, BSD 4.3, ISO 9899

asin(3), atan(3), atan2(3), cos(3), sin(3), tan(3)