LOG

Returns the common (base 10) logarithm of a numerical expression, or the logarithm to an arbitrary base if specified as the first argument. The value for which log is computed needs to be larger than 0, otherwise an error is returned. If a base is provided, it also needs to be larger than 0 and not equal to 1. You can use the function LN to compute the natural logarithm (base e).

Alias: LOG10 (does not support a custom base argument)

Syntax

LOG([<base>,] <value>);

Parameters

Parameter	Description	Supported input types
<base>	Optional. The base for the logarithm. The default base is 10.	DOUBLE PRECISION
<value>	The value for which to compute the logarithm.	DOUBLE PRECISION

Return Type

DOUBLE PRECISION

Example

This example below returns the logarithm of 64.0 to base 2:

SELECT LOG(2, 64.0);

Returns: 6

This example below returns the logarithm of 100.0 to the default base 10:

SELECT LOG(100.0), LOG10(100.0);

Returns: 2, 2

The logarithm can only be computed for values that are larger than 0. All of the functions below return an error:

SELECT LOG(0.0);
SELECT LOG(-1.0);
SELECT LOG('-Inf');

When a base is provided, it needs to be positive and not equal to zero. All of the functions below return an error:

SELECT LOG(0.0, 10.0);
SELECT LOG(-1.0, 10.0);
SELECT LOG(1.0, 10.0);
SELECT LOG('-Inf', 10.0);