# Math::Exp Method

.NET Framework 4.5

Returns e raised to the specified power.

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

## Syntax

```public:
static double Exp(
double d
)
```

#### Parameters

d
Type: System::Double

A number specifying a power.

#### Return Value

Type: System::Double
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.

## Remarks

Use the Pow method to calculate powers of other bases.

Exp is the inverse of Log.

## Examples

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

```// Example for the Math::Exp( double ) method.
using namespace System;

// Evaluate logarithmic/exponential identity with a given argument.
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.
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 ) ) );
}

int 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 );
}

/*
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
*/
```

## Version Information

#### .NET Framework

Supported in: 4.5, 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

#### .NET for Windows Store apps

Supported in: Windows 8

#### .NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

## Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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