/**************************************************************************** * libs/libc/math/lib_tanhf.c * * This file is a part of NuttX: * * Copyright (C) 2012 Gregory Nutt. All rights reserved. * Ported by: Darcy Gong * * It derives from the Rhombus OS math library by Nick Johnson which has * a compatibile, MIT-style license: * * Copyright (C) 2009, 2010 Nick Johnson * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include /**************************************************************************** * Public Functions ****************************************************************************/ float tanhf(float x) { float x0 = expf(x); float x1 = 1.0F / x0; return ((x0 + x1) / (x0 - x1)); }