The
natural logarithm of a number is its
logarithm to the
base of the mathematical constant
e, where
e is an
irrational and
transcendental approximately equal to . The natural logarithm of
x is generally written as , , or sometimes, if the base
e is implicit, simply . Parentheses are sometimes added for clarity, giving ln(
x), log
e(
x) or log(
x). This is done in particular when the argument to the logarithm is not a single symbol, to prevent ambiguity.