Binary logarithm: Difference between revisions

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The symbols '''log2''', '''lb''' or '''ld''' are used for the '''[http://en.wikipedia.org/wiki/Binary_logarithm binary logarithm]''', also called '''dual logarithm''' or '''logarithm base two'''.
{{Wikipedia}}
The '''binary logarithm''', also called '''dual logarithm''' or '''logarithm base two''' (symbols: '''log<sub>2</sub>''', '''lb''', or '''ld''') of a value ''n'' is the power to which 2 is raised to obtain ''n''. The binary logarithm of a [[frequency ratio]] measures its size in [[2/1|octave]]s. [[Interval size measure]]s proportional to the octave, such as the [[cent]], can be found by multiplying the size in octaves by a constant.  


== Log2 of the first primes ==
You can calculate the binary logarithm of ''n'' using the identity:


{| class="wikitable"
$$ \log_2(n) = \ln(n) / \ln(2) $$
! [[prime]]
 
! log2 prime
== Binary logarithms of the first primes ==
{| class="wikitable center-all"
|-
! ''p''
! log<sub>2</sub>''p''
|-
|-
| 2
| 2
| 1
| 1.000000000
|-
|-
| 3
| 3
Line 38: Line 43:
|}
|}


You can calculate the binary logarithm of n like this:
[[Category:Elementary math]]
 
[[Category:Terms]]
log2(n) = ln(n)/ln(2)
 
[[Category:Howto]]
[[Category:Math]]
[[Category:Practical help]]
[[Category:Term]]
 
[[Category:Todo:improve synopsis]]

Latest revision as of 10:17, 19 March 2026

English Wikipedia has an article on:

The binary logarithm, also called dual logarithm or logarithm base two (symbols: log2, lb, or ld) of a value n is the power to which 2 is raised to obtain n. The binary logarithm of a frequency ratio measures its size in octaves. Interval size measures proportional to the octave, such as the cent, can be found by multiplying the size in octaves by a constant.

You can calculate the binary logarithm of n using the identity:

$$ \log_2(n) = \ln(n) / \ln(2) $$

Binary logarithms of the first primes

p log2p
2 1.000000000
3 1.584962501
5 2.321928095
7 2.807354922
11 3.459431619
13 3.700439718
17 4.087462841
19 4.247927513
23 4.523561956
29 4.857980995