Home Library Learn Samples Downloads Support Community Forums
1 out of 1 rated this helpful - Rate this topic

Math.Exp Method

.NET Framework 2.0

Returns e raised to the specified power.

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

C#
C++
VB
Copy 
public static double Exp (
	double d
)
J#
Copy 
public static double Exp (
	double d
)
JScript
Copy 
public static function Exp (
	d : double
) : double

Parameters

d

A number specifying a power.

Return Value

The number e raised to the power d. If d equals NaN or PositiveInfinity, that value is returned. If d equals NegativeInfinity, 0 is returned.

Use the Pow method to calculate powers of other bases.

Exp is the inverse of Log.

The following example uses Exp to evaluate certain exponential and logarithmic identities for selected values.

C#
C++
VB
Copy 
// Example for the Math.Exp( double ) method.
using System;

class ExpDemo 
{
    public static void Main() 
    {
        Console.WriteLine( 
            "This example of Math.Exp( double ) " +
            "generates the following output.\n" );
        Console.WriteLine( 
            "Evaluate [e ^ ln(X) == ln(e ^ X) == X] " +
            "with selected values for X:" );

        UseLnExp(0.1);
        UseLnExp(1.2);
        UseLnExp(4.9);
        UseLnExp(9.9);

        Console.WriteLine( 
            "\nEvaluate these identities with " +
            "selected values for X and Y:" );
        Console.WriteLine( "   (e ^ X) * (e ^ Y) == e ^ (X + Y)" );
        Console.WriteLine( "   (e ^ X) ^ Y == e ^ (X * Y)" );
        Console.WriteLine( "   X ^ Y == e ^ (Y * ln(X))" );

        UseTwoArgs(0.1, 1.2);
        UseTwoArgs(1.2, 4.9);
        UseTwoArgs(4.9, 9.9);
    }

    // Evaluate logarithmic/exponential identity with a given argument.
    static void UseLnExp(double arg)
    {
        // Evaluate e ^ ln(X) == ln(e ^ X) == X.
        Console.WriteLine( 
            "\n      Math.Exp(Math.Log({0})) == {1:E16}\n" +
            "      Math.Log(Math.Exp({0})) == {2:E16}",
            arg, Math.Exp(Math.Log(arg)), Math.Log(Math.Exp(arg)) );
    }

    // Evaluate exponential identities that are functions of two arguments.
    static void UseTwoArgs(double argX, double argY)
    {
        // Evaluate (e ^ X) * (e ^ Y) == e ^ (X + Y).
        Console.WriteLine( 
            "\nMath.Exp({0}) * Math.Exp({1}) == {2:E16}" + 
            "\n          Math.Exp({0} + {1}) == {3:E16}", 
            argX, argY, Math.Exp(argX) * Math.Exp(argY),
            Math.Exp(argX + argY) );

        // Evaluate (e ^ X) ^ Y == e ^ (X * Y).
        Console.WriteLine( 
            " Math.Pow(Math.Exp({0}), {1}) == {2:E16}" +
            "\n          Math.Exp({0} * {1}) == {3:E16}",
            argX, argY, Math.Pow(Math.Exp(argX), argY),
            Math.Exp(argX * argY) );

        // Evaluate X ^ Y == e ^ (Y * ln(X)).
        Console.WriteLine( 
            "           Math.Pow({0}, {1}) == {2:E16}" + 
            "\nMath.Exp({1} * Math.Log({0})) == {3:E16}", 
            argX, argY, Math.Pow(argX, argY), 
            Math.Exp(argY * Math.Log(argX)) );
    }
}

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

Evaluate [e ^ ln(X) == ln(e ^ X) == X] with selected values for X:

      Math.Exp(Math.Log(0.1)) == 1.0000000000000001E-001
      Math.Log(Math.Exp(0.1)) == 1.0000000000000008E-001

      Math.Exp(Math.Log(1.2)) == 1.2000000000000000E+000
      Math.Log(Math.Exp(1.2)) == 1.2000000000000000E+000

      Math.Exp(Math.Log(4.9)) == 4.9000000000000012E+000
      Math.Log(Math.Exp(4.9)) == 4.9000000000000004E+000

      Math.Exp(Math.Log(9.9)) == 9.9000000000000004E+000
      Math.Log(Math.Exp(9.9)) == 9.9000000000000004E+000

Evaluate these identities with selected values for X and Y:
   (e ^ X) * (e ^ Y) == e ^ (X + Y)
   (e ^ X) ^ Y == e ^ (X * Y)
   X ^ Y == e ^ (Y * ln(X))

Math.Exp(0.1) * Math.Exp(1.2) == 3.6692966676192444E+000
          Math.Exp(0.1 + 1.2) == 3.6692966676192444E+000
 Math.Pow(Math.Exp(0.1), 1.2) == 1.1274968515793757E+000
          Math.Exp(0.1 * 1.2) == 1.1274968515793757E+000
           Math.Pow(0.1, 1.2) == 6.3095734448019331E-002
Math.Exp(1.2 * Math.Log(0.1)) == 6.3095734448019344E-002

Math.Exp(1.2) * Math.Exp(4.9) == 4.4585777008251705E+002
          Math.Exp(1.2 + 4.9) == 4.4585777008251716E+002
 Math.Pow(Math.Exp(1.2), 4.9) == 3.5780924170885260E+002
          Math.Exp(1.2 * 4.9) == 3.5780924170885277E+002
           Math.Pow(1.2, 4.9) == 2.4433636334442981E+000
Math.Exp(4.9 * Math.Log(1.2)) == 2.4433636334442981E+000

Math.Exp(4.9) * Math.Exp(9.9) == 2.6764450551890982E+006
          Math.Exp(4.9 + 9.9) == 2.6764450551891015E+006
 Math.Pow(Math.Exp(4.9), 9.9) == 1.1684908531676833E+021
          Math.Exp(4.9 * 9.9) == 1.1684908531676829E+021
           Math.Pow(4.9, 9.9) == 6.8067718210957060E+006
Math.Exp(9.9 * Math.Log(4.9)) == 6.8067718210956985E+006
*/
J#
Copy 
// Example for the Math.Exp( double ) method.
import System.*;

class ExpDemo
{
     public static void main(String[] args)
    {
        Console.WriteLine(("This example of Math.Exp( double ) " 
            + "generates the following output.\n"));
        Console.WriteLine(("Evaluate [e ^ ln(X) == ln(e ^ X) == X] " 
            + "with selected values for X:"));
        UseLnExp(0.1);
        UseLnExp(1.2);
        UseLnExp(4.9);
        UseLnExp(9.9);
        Console.WriteLine(("\nEvaluate these identities with " 
            + "selected values for X and Y:"));
        Console.WriteLine("   (e ^ X) * (e ^ Y) == e ^ (X + Y)");
        Console.WriteLine("   (e ^ X) ^ Y == e ^ (X * Y)");
        Console.WriteLine("   X ^ Y == e ^ (Y * ln(X))");
        UseTwoArgs(0.1, 1.2);
        UseTwoArgs(1.2, 4.9);
        UseTwoArgs(4.9, 9.9);
    } //main
   
    // Evaluate logarithmic/exponential identity with a given argument.
    static void UseLnExp(double arg) 
    {
        // Evaluate e ^ ln(X) == ln(e ^ X) == X.
        Console.WriteLine("\n     Math.Exp(Math.Log({0})) == {1}\n"
            + "     Math.Log(Math.Exp({0})) == {2}", 
            System.Convert.ToString(arg),
            ((System.Double)System.Math.Exp(
            System.Math.Log(arg))).ToString("E16"),
            ((System.Double)System.Math.Log(
            System.Math.Exp(arg))).ToString("E16"));
    } //UseLnExp
   
    // Evaluate exponential identities that are functions of two arguments.
    static void UseTwoArgs(double argX, double argY) 
    {
        // Evaluate (e ^ X) * (e ^ Y) == e ^ (X + Y).
        Console.WriteLine("\nMath.Exp({0}) * Math.Exp({1}) == {2}" 
            + "\n          Math.Exp({0} + {1}) == {3}",
            new Object[] {System.Convert.ToString(argX),
            System.Convert.ToString(argY),((System.Double )
            (System.Math.Exp(argX) * System.Math.Exp(argY))).ToString("E16"),
            ((System.Double )System.Math.Exp((argX + argY))).ToString("E16")});

        // Evaluate (e ^ X) ^ Y == e ^ (X * Y).
        Console.WriteLine(" Math.Pow(Math.Exp({0}), {1}) == {2}" 
            + "\n          Math.Exp({0} * {1}) == {3}",
            new Object[] { System.Convert.ToString(argX),
            System.Convert.ToString(argY),((System.Double)System.Math.Pow
            (System.Math.Exp(argX),argY)).ToString("E16"),
            ((System.Double)System.Math.Exp((argX * argY))).ToString("E16")});

        // Evaluate X ^ Y == e ^ (Y * ln(X)).
        Console.WriteLine("           Math.Pow({0}, {1}) == {2}" 
            + "\nMath.Exp({1} * Math.Log({0})) == {3}", 
            new Object[] { System.Convert.ToString(argX), 
            System.Convert.ToString(argY), 
            ((System.Double)System.Math.Pow(argX, argY)).ToString("E16"),
            ((System.Double)System.Math.Exp(
            (argY * System.Math.Log(argX)))).ToString("E16") });
    } //UseTwoArgs
} //ExpDemo

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

Evaluate [e ^ ln(X) == ln(e ^ X) == X] with selected values for X:

      Math.Exp(Math.Log(0.1)) == 1.0000000000000001E-001
      Math.Log(Math.Exp(0.1)) == 1.0000000000000008E-001

      Math.Exp(Math.Log(1.2)) == 1.2000000000000000E+000
      Math.Log(Math.Exp(1.2)) == 1.2000000000000000E+000

      Math.Exp(Math.Log(4.9)) == 4.9000000000000012E+000
      Math.Log(Math.Exp(4.9)) == 4.9000000000000004E+000

      Math.Exp(Math.Log(9.9)) == 9.9000000000000004E+000
      Math.Log(Math.Exp(9.9)) == 9.9000000000000004E+000

Evaluate these identities with selected values for X and Y:
   (e ^ X) * (e ^ Y) == e ^ (X + Y)
   (e ^ X) ^ Y == e ^ (X * Y)
   X ^ Y == e ^ (Y * ln(X))

Math.Exp(0.1) * Math.Exp(1.2) == 3.6692966676192444E+000
          Math.Exp(0.1 + 1.2) == 3.6692966676192444E+000
 Math.Pow(Math.Exp(0.1), 1.2) == 1.1274968515793757E+000
          Math.Exp(0.1 * 1.2) == 1.1274968515793757E+000
           Math.Pow(0.1, 1.2) == 6.3095734448019331E-002
Math.Exp(1.2 * Math.Log(0.1)) == 6.3095734448019344E-002

Math.Exp(1.2) * Math.Exp(4.9) == 4.4585777008251705E+002
          Math.Exp(1.2 + 4.9) == 4.4585777008251716E+002
 Math.Pow(Math.Exp(1.2), 4.9) == 3.5780924170885260E+002
          Math.Exp(1.2 * 4.9) == 3.5780924170885277E+002
           Math.Pow(1.2, 4.9) == 2.4433636334442981E+000
Math.Exp(4.9 * Math.Log(1.2)) == 2.4433636334442981E+000

Math.Exp(4.9) * Math.Exp(9.9) == 2.6764450551890982E+006
          Math.Exp(4.9 + 9.9) == 2.6764450551891015E+006
 Math.Pow(Math.Exp(4.9), 9.9) == 1.1684908531676833E+021
          Math.Exp(4.9 * 9.9) == 1.1684908531676829E+021
           Math.Pow(4.9, 9.9) == 6.8067718210957060E+006
Math.Exp(9.9 * Math.Log(4.9)) == 6.8067718210956985E+006
*/

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
Did you find this helpful?
(1500 characters remaining)

Community Additions

ADD
© 2013 Microsoft. All rights reserved.
|
Site Feedback
© 2013 Microsoft. All rights reserved.