1*48917Scael.\" Copyright (c) 1991 The Regents of the University of California. 2*48917Scael.\" All rights reserved. 3*48917Scael.\" 4*48917Scael.\" %sccs.include.redist.man% 5*48917Scael.\" 6*48917Scael.\" @(#)acos.3 5.1 (Berkeley) 05/02/91 7*48917Scael.\" 8*48917Scael.Dd 9*48917Scael.Dt ACOS 3 10*48917Scael.Os 11*48917Scael.Sh NAME 12*48917Scael.Nm acos 13*48917Scael.Nd arc cosine function 14*48917Scael.Sh SYNOPSIS 15*48917Scael.Fd #include <math.h> 16*48917Scael.Ft double 17*48917Scael.Fn acos "double x" 18*48917Scael.Sh DESCRIPTION 19*48917ScaelThe 20*48917Scael.Fn acos 21*48917Scaelfunction computes the principal value of the arc cosine of 22*48917Scael.Fa x . 23*48917ScaelA domain error occurs for arguments not in the range [-1, +1]. 24*48917ScaelFor a discussion of error due to roundoff, see 25*48917Scael.Xr math 3 . 26*48917Scael.Sh RETURN VALUES 27*48917ScaelThe 28*48917Scael.Fn acos 29*48917Scaelfunction returns the arc cosine in the range 30*48917Scael.Bq 0 , \*(Pi 31*48917Scaelradians. 32*48917ScaelOn the 33*48917Scael.Tn VAX 34*48917Scaeland 35*48917Scael.Tn Tahoe , 36*48917Scaelif: 37*48917Scael.Bd -unfilled -offset indent 38*48917Scael.Pf \&| Ns Ar x Ns \&| > 1 , 39*48917Scael.Ed 40*48917Scael.Pp 41*48917Scael.Fn acos x 42*48917Scaelsets the global variable 43*48917Scael.Va errno 44*48917Scaelto 45*48917Scael.Dv EDOM 46*48917Scaeland a reserved operand fault is generated. 47*48917Scael.Sh SEE ALSO 48*48917Scael.Xr sin 3 , 49*48917Scael.Xr cos 3 , 50*48917Scael.Xr tan 3 , 51*48917Scael.Xr asin 3 , 52*48917Scael.Xr atan 3 , 53*48917Scael.Xr atan2 3 , 54*48917Scael.Xr sinh 3 , 55*48917Scael.Xr cosh 3 , 56*48917Scael.Xr tanh 3 , 57*48917Scael.Xr math 3 , 58*48917Scael.Sh STANDARDS 59*48917ScaelThe 60*48917Scael.Fn acos 61*48917Scaelfunction conforms to 62*48917Scael.St -ansiC . 63