Exponential function - Wikipedia
https://en.wikipedia.org/wiki/Exponential_functionThe real exponential function is a bijection from to (;). Its inverse function is the natural logarithm, denoted ,, or ; because of this, some old texts refer to the exponential function as the antilogarithm.. The exponential function is sometimes called the natural exponential function for distinguishing it from the other exponential functions, which are the functions of the form () =, …