The comparison of 2 floating-point numbers with == is not reliable, as everyone knows. Nevertheless, it is sometimes complicated to do without it. Wouldn’t it be a good idea to integrate in the stdlib an “approximate” comparison function, such as the one defined here , and even to overload the =~ a…

I think this is mostly needed in specs, and there’s a matcher for that already: https://crystal-lang.org/api/1.0.0/Spec/Expectations.html#be_close(expected,delta)-instance-method Or were you talking about using it in regular code? What’s the use case?

Yes, I mean for standard code, not for tests, and to do what the == operator exists for, but with increased reliability, and without having to look for workarounds (with < or >) or code logic changes, and in my current development project, the use of floats cannot be avoided. According to what I re…

Comparison between two floating point values is actually exact and reliable. Imprecise is the conversion between floating point format and decimal representation. Outside of specs which test algorithms to return specific values expressed as literals, this should rarely be an issue. Can you tell us…

Reading the mentioned posts and also this blog , I was wondering about the reliability of the test x == 0.0 when x is the result of a series of calculations on a data history (which is my use case) If I understand correctly, this test will return a false result in all cases where x is not exactly eq…

It looks like you’ve already figured out a good solution, but I wanted to weigh in with something maybe obvious just because it wasn’t explicitly stated: the problem with using =~ and !~ is that they use two values (the receiver on the left side and the argument on the right), but what you want is s…

I’d almost be in favor of removing equality comparison between float and anything else. It’s dangerous! :)

Why not both? Remove equality comparisons and add def approximately(b, epsilon = {% type.default_epsilon %}) (a - b).abs < epsilon end Unity via Mathf.approximately and Julia via the ≈ operator have builtin approximate functions.

[image] Floats : equality compare Seems reasonable, to me, to have a compare with a delta in the stdlib. Or maybe it’s not useful? I think it could be useful but, as pointed out, no size will fit all use cases. Even within one project, I expect that some comparison…

A little better: struct ::Float # what are sensible defaults for `Float32` and `Float64`? # what are sensible defaults for `BigFloat` and `BigRational`? macro default_rtol {% if @type.has_constant?(:EPSILON) %} {{ @type.id }}::EPSILON * 16 #? pulled from thin air {%…

Floats : equality compare

rogerdpack May 13, 2021, 7:16pm 7

Seems reasonable, to me, to have a compare with a delta in the stdlib. Or maybe it’s not useful?

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Floats : equality compare

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