Usage of `_iszero`, `_isnotzero`

[OlivierHnt]

We are currently working on releasing the 1.0 version of IntervalArithmetic.jl (see JuliaIntervals/IntervalArithmetic.jl#698). One important decision we made is to be very strict with the usage of boolean comparison functions from Base. For instance, iszero(x::Interval) throws if x contains zero but is not thin, like $[-1, 1]$.

I noticed that you have two internal functions _iszero and _isnotzero which seems to be used only in the context "is the number exactly zero".

I found (on 1.11, but maybe also true on 1.10) that this is not used everywhere, e.g.

https://github.com/JuliaSparse/SparseArrays.jl/blob/242035184c0d539bdb5e64bf26eb7726b123db14/src/sparsevector.jl#L2384C8-L2384C21

Is it possible to replace all instances of x == zero(x) (and similar) with _iszero (or _isnotzero) ? If so, could this be backported to 1.10 and 1.11 as well?

[ViralBShah]

Should be ok in principle. Are you able to put a PR?

[SobhanMP]

I think it's probably worth reading the comments in #296, in short beware that -0 is a bit weird.

[OlivierHnt]

Thx for the heads up 🙂. I'll make a PR, we can discuss the backporting procedure then.

[LilithHafner]

I expect that you'll need to return missing or IntervalArithmatic.Unknown() or some such or declare a weak dependency on SpareArrays because iszero(x) === true still throws if iszero(x) throws.

[OlivierHnt]

Thanks for having a look at this issue. We do have SparseArrays as a weak dependency for the tentative 1.0 (JuliaIntervals/IntervalArithmetic.jl#698) which uses the _iszero and _isnotzero hooks.