In mathematics, ln stands for the sign of natural logarithm, and the constant is E (irrational number, which is about 2.7 1828 ...), that is, lnm=loge(m).

Among them, log (English noun: logarithms) stands for logarithmic operation.

When a b = n, it can also be expressed as log (a) (n) = b, where a is called "base", n is called "true number" and b is called "logarithm of n with base a". The log(a)(n) function is called logarithmic function.