Dealing with very small or very large numbers

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Anthony Gurunian
Anthony Gurunian 2021 年 4 月 10 日
コメント済み: Anthony Gurunian 2021 年 4 月 10 日
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?

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James Tursa
James Tursa 2021 年 4 月 10 日
I guess the obvious suggestion is to work in units of nanometers or maybe picometers instead of meters. Can you do that?
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Anthony Gurunian
Anthony Gurunian 2021 年 4 月 10 日
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
Anthony Gurunian 2021 年 4 月 10 日
Never mind, the quantity x is untiless in my case so it doesn't matter.

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