The `ln` function can be used in [custom filters](https://docs.cloud.google.com/looker/docs/filtering-and-limiting.md.txt#custom-filters) and [table calculations](https://docs.cloud.google.com/looker/docs/table-calculations.md.txt) to get the natural logarithm of a value.

## Syntax

**`ln(value)`**

The `ln` function takes the logarithm of a `value` to the base of the mathematical constant *e*.

## Examples

The `ln` function can be used to model exponential growth linearly by taking `ln` of the dependent variable. For example:

    ln(order_items.growth_rate)

## Things to know

`ln` can be used to give you the time needed to reach a certain level of growth.
For instance, modeling growth exponentially as:

*growth = e^time^*

*time* can be determined using `ln` as follows:

    ln(growth)