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Python Python Basics Types and Branching Numeric

Posted by Tana Guşita
Tana Guşita
190 Points

I tried something different

instead of 0.1+0.1+0.1-0.3 i wrote 0.2+0.2+0.2-0.6 and i got 1.1102230246251565e-16 is it the same as 5.5.....?

2 Answers

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

It's different, but it's also an example of how small errors will appear in floating-point calculations.

Hambone F
Hambone F
3,581 Points
Hambone F
Hambone F
3,581 Points

Interestingly - it's actually exactly twice the 5.5 number seen in the video. It kind of makes sense, double the magnitude of the inputs, double the magnitude of the error.

You can try it right in the REPL:

>>> err1 = 0.1 + 0.1 + 0.1 - 0.3
>>> err1
5.551115123125783e-17
>>> err2 = 0.2 + 0.2 + 0.2 - 0.6
>>> err2
1.1102230246251565e-16
>>> err1 * 2 == err2
True
>>>