Returns a **Double** specifying the natural logarithm of a number.

**Syntax**

**Log(**
**
number
**

**)**

The required ** number**argument is a Double or any valid numeric expression greater than zero.

**Remarks**

The natural logarithm is the logarithm to the base *e*. The constant*e* is approximately 2.718282.

You can calculate base-*n* logarithms for any number *x* by dividing the natural logarithm of *x* by the natural logarithm of *n* as follows:

Log*n**(x)* = **Log**(*x*) / **Log**(*n*)

The following example illustrates a custom **Functio****n** that calculates base-10 logarithms:

**Note:** Examples that follow demonstrate the use of this function in a Visual Basic for Applications (VBA) module. For more information about working with VBA, select **Developer Reference** in the drop-down list next to **Search** and enter one or more terms in the search box.

```
```Static Function Log10(X)

Log10 = Log(X) / Log(10#)

End Function

## Example

This example uses the **Log** function to return the natural logarithm of a number.

```
```Dim MyAngle, MyLog

' Define angle in radians.

MyAngle = 1.3

' Calculate inverse hyperbolic sine.

MyLog = Log(MyAngle + Sqr(MyAngle * MyAngle + 1))