acos, acosf - arc cosine functions

CONTENTS

Library
Synopsis
Description
Return Values
See Also
Standards

.Lb libm

.In math.h double acos double x float acosf float x

The acos and the acosf functions compute 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).

The acos and the acosf functions return the arc cosine in the range [0, pi] radians. If:

| x | > 1,

acos x raises an invalid exception and returns an NaN.

asin(3), atan(3), atan2(3), cos(3), cosh(3), fenv(3), math(3), sin(3), sinh(3), tan(3), tanh(3)

The acos function conforms to -isoC.

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