exponential function

By ‘exponential function’ is typically meant the function \(f(x)=e^x\), sometimes written as exp(\(x\)), where the base \(e\) is the Euler number, approximately 2.71828. This function is central in much of mathematics, especially calculus (because \(e^x\) is its own derivative), and is the basic model for all kinds of natural growth and decay, including the growth of populations and of interesting-bearing accounts.

More generally, an exponential function is any function of the form \(a^x\), where \(a\) is a constant.