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Math.Tanh Method

Returns the hyperbolic tangent of the specified angle.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static double Tanh(
	double value
)

Parameters

value
Type: System.Double
An angle, measured in radians.

Return Value

Type: System.Double
The hyperbolic tangent of value. If value is equal to NegativeInfinity, this method returns -1. If value is equal to PositiveInfinity, this method returns 1. If value is equal to NaN, this method returns NaN.

The angle, value, must be in radians. Multiply by Math.PI/180 to convert degrees to radians.

The following example uses Tanh to evaluate certain hyperbolic tangent identities for selected values.


// Example for the hyperbolic Math.Tanh( double ) method.
using System;

class DemoTanh 
{
    public static void Main() 
    {
        Console.WriteLine( 
            "This example of hyperbolic Math.Tanh( double )\n" +
            "generates the following output." );
        Console.WriteLine( 
            "\nEvaluate these hyperbolic identities " +
            "with selected values for X:" );
        Console.WriteLine( "   tanh(X) == sinh(X) / cosh(X)" );
        Console.WriteLine( 
            "   tanh(2 * X) == 2 * tanh(X) / (1 + tanh^2(X))" );

        UseTanh(0.1);
        UseTanh(1.2);
        UseTanh(4.9);

        Console.WriteLine( 
            "\nEvaluate [tanh(X + Y) == (tanh(X) + tanh(Y)) " +
            "/ (1 + tanh(X) * tanh(Y))]" +
            "\nwith selected values for X and Y:" );

        UseTwoArgs(0.1, 1.2);
        UseTwoArgs(1.2, 4.9);
    }

    // Evaluate hyperbolic identities with a given argument.
    static void UseTanh(double arg)
    {
        double tanhArg = Math.Tanh(arg);

        // Evaluate tanh(X) == sinh(X) / cosh(X).
        Console.WriteLine( 
            "\n                       Math.Tanh({0}) == {1:E16}\n" +
            "      Math.Sinh({0}) / Math.Cosh({0}) == {2:E16}",
            arg, tanhArg, (Math.Sinh(arg) / Math.Cosh(arg)) );

        // Evaluate tanh(2 * X) == 2 * tanh(X) / (1 + tanh^2(X)).
        Console.WriteLine( 
            "                   2 * Math.Tanh({0}) /", 
            arg, 2.0 * tanhArg );
        Console.WriteLine( 
            "             (1 + (Math.Tanh({0}))^2) == {1:E16}", 
            arg, 2.0 * tanhArg / (1.0 + tanhArg * tanhArg ) );
        Console.WriteLine( 
            "                       Math.Tanh({0}) == {1:E16}", 
            2.0 * arg, Math.Tanh(2.0 * arg) );
    }

    // Evaluate a hyperbolic identity that is a function of two arguments.
    static void UseTwoArgs(double argX, double argY)
    {
        // Evaluate tanh(X + Y) == (tanh(X) + tanh(Y)) / (1 + tanh(X) * tanh(Y)).
        Console.WriteLine( 
            "\n    (Math.Tanh({0}) + Math.Tanh({1})) /\n" + 
            "(1 + Math.Tanh({0}) * Math.Tanh({1})) == {2:E16}", 
            argX, argY, (Math.Tanh(argX) + Math.Tanh(argY)) /
            (1.0 + Math.Tanh(argX) * Math.Tanh(argY)) );
        Console.WriteLine( 
            "                       Math.Tanh({0}) == {1:E16}",
            argX + argY, Math.Tanh(argX + argY));
    }
}

/*
This example of hyperbolic Math.Tanh( double )
generates the following output.

Evaluate these hyperbolic identities with selected values for X:
   tanh(X) == sinh(X) / cosh(X)
   tanh(2 * X) == 2 * tanh(X) / (1 + tanh^2(X))

                       Math.Tanh(0.1) == 9.9667994624955819E-002
      Math.Sinh(0.1) / Math.Cosh(0.1) == 9.9667994624955819E-002
                   2 * Math.Tanh(0.1) /
             (1 + (Math.Tanh(0.1))^2) == 1.9737532022490401E-001
                       Math.Tanh(0.2) == 1.9737532022490401E-001

                       Math.Tanh(1.2) == 8.3365460701215521E-001
      Math.Sinh(1.2) / Math.Cosh(1.2) == 8.3365460701215521E-001
                   2 * Math.Tanh(1.2) /
             (1 + (Math.Tanh(1.2))^2) == 9.8367485769368024E-001
                       Math.Tanh(2.4) == 9.8367485769368024E-001

                       Math.Tanh(4.9) == 9.9988910295055444E-001
      Math.Sinh(4.9) / Math.Cosh(4.9) == 9.9988910295055433E-001
                   2 * Math.Tanh(4.9) /
             (1 + (Math.Tanh(4.9))^2) == 9.9999999385024030E-001
                       Math.Tanh(9.8) == 9.9999999385024030E-001

Evaluate [tanh(X + Y) == (tanh(X) + tanh(Y)) / (1 + tanh(X) * tanh(Y))]
with selected values for X and Y:

    (Math.Tanh(0.1) + Math.Tanh(1.2)) /
(1 + Math.Tanh(0.1) * Math.Tanh(1.2)) == 8.6172315931330645E-001
                       Math.Tanh(1.3) == 8.6172315931330634E-001

    (Math.Tanh(1.2) + Math.Tanh(4.9)) /
(1 + Math.Tanh(1.2) * Math.Tanh(4.9)) == 9.9998993913939649E-001
                       Math.Tanh(6.1) == 9.9998993913939649E-001
*/


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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