**Public Function Logarithm( _
ByVal vX As Variant _
) As Variant**

**Natural logarithm of a complex or real number. **

**Top20:** This function is among our "top-twenty" most useful.

**Examples:** Logarithm(-1) = "0|3.14159265358979"
Logarithm(0) = "#NINF"
Logarithm(1) = 0
Logarithm(2) = 0.693147180559945
Logarithm(e) = 1
Logarithm(10) = 2.30258509299405
Logarithm("2.3|-4.5") = "1.6201229253022|-1.09829939127783"

**See also:** LogBaseN Function
Log10 Function
Log Function (Visual Basic)

**vX:** Number whose natural logarithm is returned. Function returns Null if vX is Null or cannot be fixed up to a real or complex number (as defined by the ComplexStringToReals function). Complex numbers are represented within strings as "R|I" where R is the real part and I is the imaginary part. Function returns the string "#NINF" to represent negative infinity if vX is 0 (zero).

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