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Java example source code file (s_tanh.c)
The s_tanh.c Java example source code/* * Copyright (c) 1998, 2001, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* Tanh(x) * Return the Hyperbolic Tangent of x * * Method : * x -x * e - e * 0. tanh(x) is defined to be ----------- * x -x * e + e * 1. reduce x to non-negative by tanh(-x) = -tanh(x). * 2. 0 <= x <= 2**-55 : tanh(x) := x*(one+x) * -t * 2**-55 < x <= 1 : tanh(x) := -----; t = expm1(-2x) * t + 2 * 2 * 1 <= x <= 22.0 : tanh(x) := 1- ----- ; t=expm1(2x) * t + 2 * 22.0 < x <= INF : tanh(x) := 1. * * Special cases: * tanh(NaN) is NaN; * only tanh(0)=0 is exact for finite argument. */ #include "fdlibm.h" #ifdef __STDC__ static const double one=1.0, two=2.0, tiny = 1.0e-300; #else static double one=1.0, two=2.0, tiny = 1.0e-300; #endif #ifdef __STDC__ double tanh(double x) #else double tanh(x) double x; #endif { double t,z; int jx,ix; /* High word of |x|. */ jx = __HI(x); ix = jx&0x7fffffff; /* x is INF or NaN */ if(ix>=0x7ff00000) { if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ else return one/x-one; /* tanh(NaN) = NaN */ } /* |x| < 22 */ if (ix < 0x40360000) { /* |x|<22 */ if (ix<0x3c800000) /* |x|<2**-55 */ return x*(one+x); /* tanh(small) = small */ if (ix>=0x3ff00000) { /* |x|>=1 */ t = expm1(two*fabs(x)); z = one - two/(t+two); } else { t = expm1(-two*fabs(x)); z= -t/(t+two); } /* |x| > 22, return +-1 */ } else { z = one - tiny; /* raised inexact flag */ } return (jx>=0)? z: -z; } Other Java examples (source code examples)Here is a short list of links related to this Java s_tanh.c source code file: |
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