Math.Exp Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Returns e raised to the specified power.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- d
- Type: System.Double
A number specifying a power.
Return Value
Type: System.DoubleThe number e raised to the power d. If d equals NaN or PositiveInfinity, that value is returned. If d equals NegativeInfinity, 0 is returned.
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
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