ACOS(3) MachTen Programmer’s 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, pi] 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 ALSO
sin(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 C3.159-1989 (‘‘ANSI C’’).

4.4BSD June 4, 1993 1