1*48920Scael.\" Copyright (c) 1985, 1991 Regents of the University of California. 2*48920Scael.\" All rights reserved. 3*48920Scael.\" 4*48920Scael.\" %sccs.include.redist.man% 5*48920Scael.\" 6*48920Scael.\" @(#)atanh.3 5.1 (Berkeley) 05/02/91 7*48920Scael.\" 8*48920Scael.Dd 9*48920Scael.Dt ATANH 3 10*48920Scael.Os BSD 4.3 11*48920Scael.Sh NAME 12*48920Scael.Nm atanh 13*48920Scael.Nd inverse hyperbolic tangent function 14*48920Scael.Sh SYNOPSIS 15*48920Scael.Fd #include <math.h> 16*48920Scael.Ft double 17*48920Scael.Fn atanh "double x" 18*48920Scael.Sh DESCRIPTION 19*48920ScaelThe 20*48920Scael.Fn atanh 21*48920Scaelfunction computes the inverse hyperbolic tangent 22*48920Scaelof the real 23*48920Scaelargument 24*48920Scael.Ar x . 25*48920ScaelFor a discussion of error due to roundoff, see 26*48920Scael.Xr math 3 . 27*48920Scael.Sh RETURN VALUES 28*48920ScaelThe 29*48920Scael.Fn atanh 30*48920Scaelfunction 31*48920Scaelreturns the inverse hyperbolic tangent of 32*48920Scael.Ar x 33*48920Scaelif successful. 34*48920ScaelOn the 35*48920Scael.Tn VAX 36*48920Scaeland 37*48920Scael.Tn Tahoe , 38*48920Scaelif the argument has absolute value 39*48920Scaelbigger than or equal to 1, 40*48920Scael.Fn atanh 41*48920Scaelsets the global variable 42*48920Scael.Va errno 43*48920Scaelto 44*48920Scael.Er EDOM 45*48920Scaeland 46*48920Scaela reserved operand fault is generated. 47*48920Scael.Sh SEE ALSO 48*48920Scael.Xr acosh 3 , 49*48920Scael.Xr asinh 3 , 50*48920Scael.Xr exp 3 , 51*48920Scael.Xr infnan 3 52*48920Scael.Xr math 3 , 53*48920Scael.Sh AUTHOR 54*48920Scael.An W. Kahan , 55*48920Scael.An Kwok\-Choi Ng 56*48920Scael.Sh HISTORY 57*48920ScaelThe 58*48920Scael.Fn atanh 59*48920Scaelfunction appeared in 60*48920Scael.Bx 4.3 . 61