The integer part of a binary logarithm can be found use the find first put operation on an integer value, or by looking up the exponent of a floating point value. Historically, the first application of binary logarithms was in music theory, by Leonhard Euler: the binary logarithm of a frequency ratio of two musical tones gives the number of octaves by which the tones differ. The modern form of a binary logarithm, using to any number (not exactly powers of two) was considered explicitly by Leonhard Euler in 1739.As part of his work in this area, Euler published a table of binary logarithms of the integers from 1 to 8, to seven decimal digits of accuracy. Euler established the application of binary logarithms to music theory, long before their applications in information theory and computer science became known.

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```
package com.algorithmexamples.math
fun log2(x: Int) = Math.log(x.toDouble()) / Math.log(2.toDouble())
```