In
mathematics, the
common logarithm is the
logarithm with base 10. It is also known as the
decadic logarithm and also as the
decimal logarithm, named after its base, or
Briggsian logarithm, after
Henry Briggs, an English mathematician who pioneered its use, as well as "standard logarithm". It is indicated by log
10(
x), or sometimes Log(
x) with a capital
L (however, this notation is ambiguous since it can also mean the complex natural logarithmic
multi-valued function). On calculators it is usually "log", but
mathematicians usually mean
natural logarithm (logarithm with base e ˜ 2.71828) rather than common logarithm when they write "log". To mitigate this ambiguity the
ISO 80000 specification recommends that log
10(
x) should be written lg (
x) and log
e(
x) should be ln (
x).