Binary logarithm: Difference between revisions

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{{Wikipedia| Binary logarithm }}
{{Wikipedia}}
The symbols '''log2''', '''lb''' or '''ld''' are used for the '''binary logarithm''', also called '''dual logarithm''' or '''logarithm base two'''.
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:


$$ \log_2(n) = \ln(n) / \ln(2) $$
== Binary logarithms of the first primes ==
{| class="wikitable center-all"
{| class="wikitable center-all"
! [[Prime]]
|-
! Log2 prime
! ''p''
! log<sub>2</sub>''p''
|-
|-
| 2
| 2
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|}
|}


You can calculate the binary logarithm of ''n'' using the identity:
$$ \log_2(n) = \ln(n) / \ln(2) $$
[[Category:Math]]
[[Category:Elementary math]]
[[Category:Elementary math]]
[[Category:Terms]]
[[Category:Terms]]
{{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