acos()

NAME

acos() - arc cosine function

SYNOPSIS

#include <math.h>


double acos (double x)

DESCRIPTION

The acos(3) 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(3) function returns the arc cosine in the range [0, pi] radians.

If x is outside that range, acos sets the global variable errno to [EDOM] and returns an indefinite.

ERRORS

acos(3) can set errno to:

[EDOM]

The value of x was less than -1 or greater than 1.

SEE ALSO

sin(3)

cos(3)

tan(3)

asin(3)

atan(3)

atan2(3)

sinh(3)

cosh(3)

tanh(3)