acos

Syntax

#include <math.h> double acos(double x);

Description

This function returns the angle in the range [0..Pi] radians whose cosine is x. If the absolute value of x is greater than 1, a domain error occurs, and errno is set to EDOM.

Return Value

The arc cosine, in radians, of x. If the absolute value of x is greater than 1, the function returns a NaN.

Portability

ANSI/ISO C	C89; C99
POSIX	1003.2-1992; 1003.1-2001