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Math function
LOG
Returns the logarithm to a base you choose, base 10 by default.
OccasionalDifficulty 1200 · ProficientUsage rank #191 of 520
When to use it
Logarithm in any base you choose. With one argument it is base 10. Useful for "how many doublings", digit counts, and decibel-style scales.
The shape of it
- Syntax
=LOG(number, [base])
Worked examples
Base 10
=LOG(100) → 2
Base 10 by default.
Base 2
=LOG(8,2) → 3
How many doublings from 1 to 8.
Order of magnitude
=LOG(1000000) → 6
Order of magnitude of a million.
Worth knowing
- Number of digits in an integer: =INT(LOG(n))+1.
- Half-lives: =LOG(remaining/start,0.5).
- LOG(x,base) equals LN(x)/LN(base) if you need it in a language without arbitrary bases.
Where it goes wrong
- #NUM! for zero or negative numbers, and #DIV/0! for base 1.
- LOG(x) is base 10, not base e; use LN for natural logs.
Related
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