Dealing with very small or very large numbers

I have a physical problem with length scales on the order of nanometers. After some calculations, I have to calculate things like exp(-1e15) which is 0 according to MATLAB, but in reality it is nonzero. For context exp(-700) is already 9.8e-305 which is close to the smallest number in MATLAB 2.2251e-308. Is there a known workaround for things like his?

Answer 1

[James Tursa]

I guess the obvious suggestion is to work in units of nanometers or maybe picometers instead of meters. Can you do that?

[Anthony Gurunian]

That creates a new problem of having to convert back. Let's say I need a quantity f(x) = e^-x. If x is in meters f(1000) = 5.07e-435. if x is in kilometers, f(1) = 0.36. There is no simple way to convert.

[Anthony Gurunian]

Never mind, the quantity x is untiless in my case so it doesn't matter.