Logarithm

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Logarithms or logs are a concept of mathematics. A log is the inverse of exponentiation; this is, it tells you what exponent is needed to make a certain number. So since

2^3= 2 \times 2 \times 2=8,

the logarithm to a base 2 of 8 is 3, written thus:

\log_2(8) = 3\

Logarithms to base 10 are known as common logs and are usually written without the base; for example:

\log(100) = 2\ because 10^2 = 100\


[edit] Commmon bases for logarithms

base abbreviation Comments
2 lg Very common in Computer Science
e ln The base of this is the Eulerian number e, which is 2.718...
10 log
any other number, n logn This is the general way to write logarithms