E(自然对数定义)
彩色的定义
##阅读更多-[指数函数和e的直观指南](//www.i494.com/articles/an-intuitive-guide-to-exponential-functions-e/) - [e的常见定义(彩色)](//www.i494.com/articles/definitions-of-e-colorized/) -[揭开自然对数的神秘](//www.i494.com/articles/demystifying-the-natural-logarithm-ln/)