The natural logarithm in the field of mathematics is represented by ln, the first letter is lowercase L, not uppercase I, and Ln is the natural logarithm ln a=loge? A. Logarithms based on e are usually used for ln, and e is also a transcendental number. E is widely used in science and technology, and the logarithm with the base of 10 is generally not used. Taking e as the base can simplify many formulas, and it is the most "natural", so it is called "natural logarithm" 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.