1*61283Sbostic.\" Copyright (c) 1991, 1993 2*61283Sbostic.\" The Regents of the University of California. All rights reserved. 348918Scael.\" 449229Scael.\" %sccs.include.redist.roff% 548918Scael.\" 6*61283Sbostic.\" @(#)acosh.3 8.1 (Berkeley) 06/04/93 748918Scael.\" 848918Scael.Dd 948918Scael.Dt ACOSH 3 1048918Scael.Os BSD 4.3 1148918Scael.Sh NAME 1248918Scael.Nm acosh 1348918Scael.Nd inverse hyperbolic cosine function 1448918Scael.Sh SYNOPSIS 1548918Scael.Fd #include <math.h> 1648918Scael.Ft double 1748918Scael.Fn acosh "double x" 1848918Scael.Sh DESCRIPTION 1948918ScaelThe 2048918Scael.Fn acosh 2148918Scaelfunction computes the inverse hyperbolic cosine 2248918Scaelof the real 2348918Scaelargument 2448918Scael.Ar x . 2548918ScaelFor a discussion of error due to roundoff, see 2648918Scael.Xr math 3 . 2748918Scael.Sh RETURN VALUES 2848918ScaelThe 2948918Scael.Fn acosh 3048918Scaelfunction 3148918Scaelreturns the inverse hyperbolic cosine of 3248918Scael.Ar x . 3348918ScaelOn the 3448918Scael.Tn VAX 3548918Scaeland 3648918Scael.Tn Tahoe , 3748918Scaelif the argument is less than one 3848918Scael.Fn acosh 3948918Scaelsets the global variable 4048918Scael.Va errno 4148918Scaelto 4248918Scael.Er EDOM 4348918Scaeland 4448918Scaelcauses a reserved operand fault. 4548918Scael.Sh SEE ALSO 4648918Scael.Xr asinh 3 , 4748918Scael.Xr atanh 3 , 4848918Scael.Xr exp 3 , 4948918Scael.Xr infnan 3 5048918Scael.Xr math 3 , 5148918Scael.Sh HISTORY 5248918ScaelThe 5348918Scael.Fn acosh 5448918Scaelfunction appeared in 5548918Scael.Bx 4.3 . 56