Java tan tanh(double x)

Description

A function that returns the hyperbolic tangent of its argument.

License

Open Source License

Parameter

Parameter	Description
x	the argument

Declaration

public static double tanh(double x) 

Method Source Code

//package com.java2s;
/*/*w  w  w . j  a va 2  s .co  m*/
 * Copyright 1998-2007 The Brookings Institution, NuTech Solutions,Inc., Metascape LLC, and contributors. 
 * All rights reserved.
 * This program and the accompanying materials are made available solely under the BSD license "ascape-license.txt".
 * Any referenced or included libraries carry licenses of their respective copyright holders. 
 */

public class Main {
    /**
     * A function that returns the hyperbolic tangent of its argument.
     * Note that this method has its worst precision around |x| = 1.0e-6,
     * but it always provides at least 11 significant digits
     * @param x  the argument
     */
    public static double tanh(double x) {
        double absX = Math.abs(x);

        if (absX > 22.0) {
            // tanh(22) equals 0.9999999999999999998 which equals 1.0 to within double precision
            return (x > 0.0) ? 1.0 : -1.0;
        } else if (absX > 1.0e-6) {
            double expX = Math.exp(x);
            double expMX = Math.exp(-x);
            return (expX - expMX) / (expX + expMX);
        } else {
            // absX <= 1.0e-6
            return x;
        }
    }
}

Related

1. tan(Number x)
2. tan(Short a)
3. tanD(double arg)
4. tand(double x)
5. tanf(float f)
6. tanh(double x)