This is a real basic question.
Why is $e$ the base for polar form of complex numbers?
In high school maths I learned that e is useful in derivatives etc. And it's conventional to use it for exponential growth/decay functions, although really we could use any base number for them if we tweak the exponent appropriately (eg. $Ae^t = Ax^{kt})$ for appropriate values of x and k).
So could any number be used as the base for polar form of complex numbers? Is $e$ just convention or is there some special relationship to $i$ that makes this work?
