Hi.
On May 24, 2011, at 5:50 PM, Matthew Rocklin wrote:
> Hi Everyone,
>
> I'm revamping Sets a bit as a precursor to my GSoC project. The first part of
> this is creating a FiniteSet object to go along with Intervals (like (0, 1] )
> and Unions (like [-1,0) U (0, 1] ).
>
> I changed the default behavior of Interval(1,1) (interval from 1 to 1
> inclusive, i.e. [1, 1] ) to be just the FiniteSet {1} .
>
> Unfortunately it appears that Interval(a,a) has been used extensively in the
> inequalities module for things like
>
> reduce_poly_inequalities([[Eq(x**2, 1)]], x, relational=False) ==
> [Interval(-1,-1), Interval(1, 1)]
>
> My code changes the result to the FiniteSet {-1, 1} which I think makes more
> sense. I'm a little uneasy about going in and changing this much in modules
> with which I have little experience. Are people ok with this? Is there anyone
> I should converse with while dealing with this particular problem? (someone
> involved in inequalities)
>
> Best,
> -Matt
>
So first off, you should run the tests. If they still pass, then it means that
the code still works. This is why we have tests.
In this particular case, I think it's fine. That probably would have used a
finite set anyway, if they had existed at the time. Mateusz wrote this code,
so he could tell you more. But I personally am +1 to making Interval(a, a)
return FiniteSet(a).
Aaron Meurer
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