view src/samer/functions/Tanh.java @ 0:bf79fb79ee13

Initial Mercurial check in.

/*
 *	Copyright (c) 2000, Samer Abdallah, King's College London.
 *	All rights reserved.
 *
 *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
 *	without even the implied warranty of MERCHANTABILITY or 
 *	FITNESS FOR A PARTICULAR PURPOSE.
 */

package samer.functions;
import  samer.maths.*;

public class Tanh extends Function
{
	public double apply(double t) { return Mathx.tanh(t); } 
	public String   format(String arg) { return "tanh("+arg+")"; }
	public Function inverse() { return new Atanh(); }
	public Function derivative() { 
		return new Function() {
			public double apply(double t) { 
				double z=Math.exp(-t);
				z=2/(z+1/z);
				return z*z; 
			}
			public String format(String arg) { return "tanh'("+arg+")"; }
		};
	}
}