PostgreSQL ln() Function

The PostgreSQL ln() function returns the natural logarithm of the number specified by the argument.

ln() Syntax

This is the syntax of the PostgreSQL ln() function:

ln(numeric_value) -> double precision

Parameters

numeric_value

Required. A number whose logarithm needs to be obtained.

Return value

The PostgreSQL ln() function returns the natural logarithm of the number specified by the argument.

The ln() function will return NULL if the argument is NULL.

If the argument is zero, PostgreSQL will give an error: “Cannot take logarithm of zero”.

If the argument is negative, PostgreSQL will give an error: “Cannot take logarithm of negative number”.

PostgreSQL will give an error if you supply a parameter that is not a numeric type.

ln() Examples

Here are a few examples of the ln() function:

SELECT
    ln(1) AS "ln(1)",
    ln(2) AS "ln(-2)",
    ln(3.3) AS "ln(3.3)";

 ln(1) |       ln(-2)       |      ln(3.3)
-------+--------------------+--------------------
     0 | 0.6931471805599453 | 1.1939224684724346