Math.Exp Method

Returns e raised to the specified power.

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

'Declaration
<SecuritySafeCriticalAttribute> _
Public Shared Function Exp ( _
	d As Double _
) As Double

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.

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.


' Example for the Math.Exp( Double ) method.

Module Example

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      outputBlock.Text &= _
          "This example of Math.Exp( Double ) " & _
          "generates the following output." & vbCrLf & vbCrLf
      outputBlock.Text &= _
          "Evaluate [e ^ ln(X) == ln(e ^ X) == X] " & _
          "with selected values for X:" & vbCrLf

      UseLnExp(outputBlock, 0.1)
      UseLnExp(outputBlock, 1.2)
      UseLnExp(outputBlock, 4.9)
      UseLnExp(outputBlock, 9.9)

      outputBlock.Text &= vbCrLf & _
          "Evaluate these identities with selected values for X and Y:" & vbCrLf
      outputBlock.Text &= "   (e ^ X) * (e ^ Y) = e ^ (X + Y)" & vbCrLf
      outputBlock.Text &= "   (e ^ X) ^ Y = e ^ (X * Y)" & vbCrLf
      outputBlock.Text &= "   X ^ Y = e ^ (Y * ln(X))" & vbCrLf

      UseTwoArgs(outputBlock, 0.1, 1.2)
      UseTwoArgs(outputBlock, 1.2, 4.9)
      UseTwoArgs(outputBlock, 4.9, 9.9)
   End Sub 'Main

   ' Evaluate logarithmic/exponential identity with a given argument.
   Sub UseLnExp(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal arg As Double)

      ' Evaluate e ^ ln(X) = ln(e ^ X) = X.
      outputBlock.Text &= String.Format( _
          vbCrLf & "      Math.Exp(Math.Log({0})) = {1:E16}" + _
          vbCrLf & "      Math.Log(Math.Exp({0})) = {2:E16}", _
          arg, Math.Exp(Math.Log(arg)), Math.Log(Math.Exp(arg))) & vbCrLf
   End Sub 'UseLnExp

   ' Evaluate exponential identities that are functions of two arguments.
   Sub UseTwoArgs(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal argX As Double, ByVal argY As Double)

      ' Evaluate (e ^ X) * (e ^ Y) = e ^ (X + Y).
      outputBlock.Text &= String.Format( _
          vbCrLf & "Math.Exp({0}) * Math.Exp({1}) = {2:E16}" + _
          vbCrLf & "          Math.Exp({0} + {1}) = {3:E16}", _
          argX, argY, Math.Exp(argX) * Math.Exp(argY), _
          Math.Exp((argX + argY))) & vbCrLf

      ' Evaluate (e ^ X) ^ Y = e ^ (X * Y).
      outputBlock.Text &= String.Format( _
          " Math.Pow(Math.Exp({0}), {1}) = {2:E16}" + _
          vbCrLf & "          Math.Exp({0} * {1}) = {3:E16}", _
          argX, argY, Math.Pow(Math.Exp(argX), argY), _
          Math.Exp((argX * argY))) & vbCrLf

      ' Evaluate X ^ Y = e ^ (Y * ln(X)).
      outputBlock.Text &= String.Format( _
          "           Math.Pow({0}, {1}) = {2:E16}" + _
          vbCrLf & "Math.Exp({1} * Math.Log({0})) = {3:E16}", _
          argX, argY, Math.Pow(argX, argY), _
          Math.Exp((argY * Math.Log(argX)))) & vbCrLf

   End Sub 'UseTwoArgs
End Module '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


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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