Cambridge IGCSE Additional Mathematics · Syllabus 0606 · Logarithmic and Exponential Functions
Natural Logarithm
What is Natural Logarithm?
The logarithm to base e, written ln x, where e is the irrational constant 2.718 to three decimal places. It is the inverse function of the exponential function e to the power x, so ln of e to the power x equals x for every real x, and e to the power ln x equals x for every positive x. Its domain is x greater than zero, its range is all real numbers, it crosses the x-axis at the point one comma zero, it has the vertical asymptote x equals zero, and it is increasing throughout its domain.
This definition is part of the Logarithmic and Exponential Functions chapter in Cambridge IGCSE Additional Mathematics.