Type piracy with the union operator

[dpsanders]

Loading this package pirates the union operator from IntervalArithmetic.
I guess this is OK but it should be documented.

[AnderGray]

This is a good point. We'll make a note of it in the documentation. I believe using hull between intervals should have the same functionality

[abraunst]

To me, it seems that this is a "bug" in IntervalArithmetic, as the union of two interval is not necessary an interval (and the convex hull is different from the union in general!). So IntervalArithmetic maybe should define hull but not union ?

[dpsanders]

I take your point, but I want to be able to use ∪ for two intervals and stay within the (standard) interval world.
If you want the interval union version, you can use IntervalUnions as your inputs I guess (even though they have a single interval inside).

Also, what should union give if the intervals overlap (in the IntervalUnion case)? There are type-stability, and hence performance, issues to be careful with. The answer should always be an IntervalUnion, even if there's only a single interval.

[abraunst]

I take your point, but I want to be able to use ∪ for two intervals and stay within the (standard) interval world. If you want the interval union version, you can use IntervalUnions as your inputs I guess (even though they have a single interval inside).

I see :) Forgive me for the question, but why is it important to use ∪ instead of hull? I'm using IntervalUnionArithmetic probably in a rather atypical way (and don't use IntervalArithmetic directly yet) so maybe I don't see the full picture. But it's super useful to me (so thanks both by the way)! At the moment the type piracy thing is a bit ugly, at the very least because it gives a warning in precompilation.

Also, what should union give if the intervals overlap (in the IntervalUnion case)? There are type-stability, and hence performance, issues to be careful with. The answer should always be an IntervalUnion, even if there's only a single interval.

Yes, agreed... hull on the other hand could and should always return an Interval.