ACOS(3) BSD Library Functions Manual ACOS(3)NAME
acos — arc cosine function
SYNOPSIS
#include <math.h>
double
acos(double x);
DESCRIPTION
The acos() function computes the principal value of the arc cosine of x.
A domain error occurs for arguments not in the range [-1, +1]. For a
discussion of error due to roundoff, see math(3).
RETURN VALUES
The acos() function returns the arc cosine in the range [0, π] radians.
On the VAX and Tahoe, if:
|x| > 1,
acos(x) sets the global variable errno to EDOM and a reserved operand
fault is generated.
SEE ALSOsin(3), cos(3), tan(3), asin(3), atan(3), atan2(3), sinh(3), cosh(3),
tanh(3), math(3),
STANDARDS
The acos() function conforms to ANSI X3.159-1989 (“ANSI C89”).
BSD June 4, 1993 BSD