Log Function
System.Math
Math.Log(d
)
or:
Math.Log(a
,newbase
)
d
or a
(required; Double)A numeric expression greater than zero
newbase
(required; Double)The base of the logarithm
Double
Returns the natural (base e) logarithm of a given number (the first syntax) or the logarithm of a given number in a specified base (the second syntax)
The natural logarithm is the logarithm base e, a constant whose value is approximately 2.718282. The natural logarithm satisfies the equation:
e^Log(x) = x
In other words, the natural logarithm function is the inverse function of the exponential function.
d
or a
, the
value whose natural logarithm the function is to return, must be a
positive real number. If number is negative or zero, the function
generates runtime error 5, “Invalid procedure call
or argument.”
This is a Shared member, so it can be used without creating any objects.
You can calculate base-n
logarithms for
any number, x
, by dividing the natural
logarithm of x
by the natural logarithm of
n
, as the following expression
illustrates:
Logn
(x
) = Log(x
) / Log(n
)
For example, the Log10 function shows the source code for a custom function that calculates base-10 logarithms:
Static Function Log10(X) Log10 = Log(X) / Log(10#) End Function
The inverse trigonometric functions, which are not intrinsic to VB, can be computed using the value returned by the Log function. The functions and their formulas are:
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