.\" Copyright (c) 1991 The Regents of the University of California. .\" All rights reserved. .\" .\" %sccs.include.redist.man% .\" .\" @(#)tanh.3 5.1 (Berkeley) 05/02/91 .\" .Dd .Dt TANH 3 .Os .Sh NAME .Nm tanh .Nd hyperbolic tangent function .Sh SYNOPSIS .Fd #include .Ft double .Fn tanh "double x" .Sh DESCRIPTION The .Fn tanh function computes the hyperbolic tangent of .Fa x . For a discussion of error due to roundoff, see .Xr math 3 . .Sh RETURN VALUES The .Fn tanh function returns the hyperbolic tangent value. .Sh SEE ALSO .Xr acos 3 , .Xr asin 3 , .Xr atan 3 , .Xr atan2 3 , .Xr cos 3 , .Xr cosh 3 , .Xr sin 3 , .Xr sinh 3 , .Xr tan 3 , .Xr math 3 , .Sh STANDARDS The .Fn tanh function conforms to .St -ansiC .