size, but when it grows at 30% of its size. If an exponentially growing function grows at a rate that is 3 times its present size, then it always grows at a rate that is 3 times its present size: when it is 10 times as big as it is now, it will grow 10 times as fast. On the other hand, functions may also grow faster than exponentially, for instance, the factorial or double exponential function.

If the constant of proportionality is negative, then