1.\" $OpenBSD: acos.3,v 1.7 2000/03/02 00:29:49 todd Exp $ 2.\" Copyright (c) 1991 The Regents of the University of California. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. All advertising materials mentioning features or use of this software 14.\" must display the following acknowledgement: 15.\" This product includes software developed by the University of 16.\" California, Berkeley and its contributors. 17.\" 4. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" from: @(#)acos.3 5.1 (Berkeley) 5/2/91 34.\" 35.Dd May 2, 1991 36.Dt ACOS 3 37.Os 38.Sh NAME 39.Nm acos , 40.Nm acosf 41.Nd arc cosine functions 42.Sh SYNOPSIS 43.Fd #include <math.h> 44.Ft double 45.Fn acos "double x" 46.Ft float 47.Fn acosf "float x" 48.Sh DESCRIPTION 49The 50.Fn acos 51and 52.Fn acosf 53functions compute the principal value of the arc cosine of 54.Fa x 55in the range 56.Bq 0 , \*(Pi . 57.Sh RETURN VALUES 58If |x|>1, 59.Fn acos "x" 60and 61.Fn acosf "x" 62sets the global variable 63.Va errno 64to EDOM. 65.Sh SEE ALSO 66.Xr asin 3 , 67.Xr atan 3 , 68.Xr atan2 3 , 69.Xr cos 3 , 70.Xr cosh 3 , 71.Xr math 3 , 72.Xr sin 3 , 73.Xr sinh 3 , 74.Xr tan 3 , 75.Xr tanh 3 76