/********************************************************************** * Copyright (c) Digital Equipment Corporation 1984, 1985, 1986. * * All Rights Reserved. * * Reference "/usr/src/COPYRIGHT" for applicable restrictions. * **********************************************************************/ /* * SCCSID: @(#)tanh.c 3.0 4/22/86 */ /* tanh(arg) computes the hyperbolic tangent of its floating point argument. sinh and cosh are called except for large arguments, which would cause overflow improperly. */ double sinh(), cosh(); double tanh(arg) double arg; { double sign; sign = 1.; if(arg < 0.){ arg = -arg; sign = -1.; } if(arg > 21.) return(sign); return(sign*sinh(arg)/cosh(arg)); }