Binary logarithm
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. It is part of the conversion formula for frequency ratio to interval size in cents.
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 |