LOG

Syntax

LOG(X), LOG(B,X)

Description

If called with one parameter, this function returns the natural logarithm of X. If X is less than or equal to 0, then NULL is returned.

If called with two parameters, it returns the logarithm of X to the base B. If B is <= 1 or X <= 0, the function returns NULL.

If any argument is NULL, the function returns NULL.

The inverse of this function (when called with a single argument) is the EXP() function.

Examples

LOG(X):

SELECT LOG(2); +-------------------+ | LOG(2) | +-------------------+ | 0.693147180559945 | +-------------------+  SELECT LOG(-2); +---------+ | LOG(-2) | +---------+ | NULL | +---------+

LOG(B,X)

SELECT LOG(2,16); +-----------+ | LOG(2,16) | +-----------+ | 4 | +-----------+  SELECT LOG(3,27); +-----------+ | LOG(3,27) | +-----------+ | 3 | +-----------+  SELECT LOG(3,1); +----------+ | LOG(3,1) | +----------+ | 0 | +----------+  SELECT LOG(3,0); +----------+ | LOG(3,0) | +----------+ | NULL | +----------+

_{This page is licensed: GPLv2, originally from fill_help_tables.sql}