On Sunday, 16 April 2023 at 14:31:43 UTC-7 aw wrote:

Awesome, let's talk about floating point semantics. [...]
We zero-pad the 1.1 to whatever length is needed to match the other number.
Because we see 1.1 as a shorthand for 1.1000000000000....  (infinitely many 
zeros)


That's the ordinary-person semantics of the string "1.1".


That's not floating-point semantics. That's just a funny way of writing 
11/10. Those are also not the semantics that scientific calculators use (or 
excel for that matter), so I suspect that "ordinary persons" are already 
quite used to 1.1 not meaning an exact  rational number but a possible 
approximation to something quite close to 11/10. In fact, I've seen people 
use this as an argument why standard units are more precise than metric: 
one would talk about 5/16 in, but that is only approximately 0.79375 cm 
(I'm not saying I'm convinced by the argument, but it is a good 
illustration that ordinary people are quite aware of rounding errors in 
decimal fraction notation)

The fact that computers often don't use base-10 floating point but base-2 
floating point is a more subtle trap, but once you're realizing that doing 
floating point arithmetic quickly leads to not all your digits being 
accurate, those difference tend to only be in digits that you shouldn't be 
trusting anyway. 

Perhaps you're interested in exploring RealLazyField. It actually attempts 
to provide a framework to compute with (some) real numbers exactly. I don't 
think it's ready to be the default just yet, if ever.

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