log()

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The log() CSS function is an exponential function that returns the logarithm of a number.

The logarithm, or log, is the inverse of exponentiation; it is the number that a fixed base has to be raised to in order to yield the number passed as the first parameter.

In CSS, when a single parameter is passed, the natural logarithm e, or approximately 2.7182818, is used, though the base can be set to any value with an optional second parameter.

Syntax

/* A <number> value */
width: calc(100px * log(7.389));  /* 200px */
width: calc(100px * log(8, 2));   /* 300px */
width: calc(100px * log(625, 5)); /* 400px */

Parameters

The log(value [, base]?) function accepts two comma-separated values as its parameters.

value

A calculation which resolves to a <number> greater than or equal to 0. Representing the value to be logarithmed.

base

Optional. A calculation which resolves to a <number> greater than or equal to 0. Representing the base of the logarithm. If not defined, the default logarithmic base e is used.

Return value

The logarithm of value, when base is defined.

The natural logarithm (base e) of value, when base is not defined.

Formal syntax

<log()> = 
log( <calc-sum> , <calc-sum>? )

<calc-sum> =
<calc-product> [ [ '+' | '-' ] <calc-product> ]*

<calc-product> =
<calc-value> [ [ '*' | '/' ] <calc-value> ]*

<calc-value> =
<number> |
<dimension> |
<percentage> |
<calc-constant> |
( <calc-sum> )

<calc-constant> =
e |
pi |
infinity |
-infinity |
NaN

Specifications

Specification
Unknown specification
# exponent-funcs

Browser compatibility

BCD tables only load in the browser

See also