Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

Math.Log Method (Double)

 

Returns the natural (base e) logarithm of a specified number.

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

Public Shared Function Log (
	d As Double
) As Double

Parameters

d
Type: System.Double

The number whose logarithm is to be found.

Return Value

Type: System.Double

One of the values in the following table.

d parameter

Return value

Positive

The natural logarithm of d; that is, ln d, or log ed

Zero

NegativeInfinity

Negative

NaN

Equal to NaN

NaN

Equal to PositiveInfinity

PositiveInfinity

Parameter d is specified as a base 10 number.

The following example illustrates the Log method.

Module Example
   Sub Main()
      Console.WriteLine( _
         "  Evaluate this identity with selected values for X:")
      Console.WriteLine("                              ln(x) = 1 / log[X](B)")
      Console.WriteLine()

      Dim XArgs() As Double = { 1.2, 4.9, 9.9, 0.1 }

      For Each argX As Double In XArgs
         ' Find natural log of argX.
         Console.WriteLine("                      Math.Log({0}) = {1:E16}", _
                           argX, Math.Log(argX))

         ' Evaluate 1 / log[X](e).
         Console.WriteLine("             1.0 / Math.Log(e, {0}) = {1:E16}", _
                           argX, 1.0 / Math.Log(Math.E, argX))
         Console.WriteLine()
      Next
   End Sub 
End Module
' This example displays the following output:
'         Evaluate this identity with selected values for X:
'                                     ln(x) = 1 / log[X](B)
'       
'                             Math.Log(1.2) = 1.8232155679395459E-001
'                    1.0 / Math.Log(e, 1.2) = 1.8232155679395459E-001
'       
'                             Math.Log(4.9) = 1.5892352051165810E+000
'                    1.0 / Math.Log(e, 4.9) = 1.5892352051165810E+000
'       
'                             Math.Log(9.9) = 2.2925347571405443E+000
'                    1.0 / Math.Log(e, 9.9) = 2.2925347571405443E+000
'       
'                             Math.Log(0.1) = -2.3025850929940455E+000
'                    1.0 / Math.Log(e, 0.1) = -2.3025850929940455E+000

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
Show: