Here you can find the source of acosh(double x)
public static double acosh(double x)
//package com.java2s; /******************************************************************** Copyright (c) 2000-2008 Steven E. Hugg.//from ww w.j a va 2 s. c o m This file is part of Exoflight. Exoflight is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Exoflight 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 for more details. You should have received a copy of the GNU General Public License along with Exoflight. If not, see <http://www.gnu.org/licenses/>. *********************************************************************/ public class Main { public static double acosh(double x) { return Math.log(x + Math.sqrt(x * x - 1)); } }