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Floating point Maths (programming.dev)

submitted 7 months ago by [email protected] to c/[email protected]

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Courtesy of @[email protected] though not sure if he's the original author of it.

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[–] [email protected] 9 points 7 months ago* (last edited 7 months ago) (1 children)

The example is wrong, because they used 1.0.

But in general x-x does not have to equal 0, that is true. I'm pretty sure Nan and infinity would yield not 0.0, but Nan instead.

And if you reach x with two different calculations, e.g. x1 = a - b - c and x2 = a - c - b it is certainly not guaranteed that x1 - x2 == 0.0

[–] [email protected] 6 points 7 months ago

This is correct. Additionally, if x is NaN, then x ≠ x.