I was going to suggest this too, but the RIF behaves differently than
you might naively expect "intervals" of real number to behave. For
example, "union" means convex hull:
sage: a = RIF(0,1)
sage: b = RIF(2,3)
sage: a.union(b).endpoints()
(0.000000000000000, 3.00000000000000)
Also, it seems from the documentation that RIF intervals are only
designed to represent closed intervals { x : a <= x <= b }
It seems like it would be relatively easy to implement a Sage class
for real intervals that represents finite unions of open, closed, half
open, and unbounded intervals and implements union() and
intersection() methods.
-Benjamin Jones
On Dec 9, 8:21 pm, Marshall Hampton <hampto...@gmail.com> wrote:
> I think you want the RealIntervalField. For exampe:
>
> sage: a = RIF(0,1)
> sage: b = RIF(.5,pi)
> sage: a.overlaps(b)
> True
>
> see:http://www.sagemath.org/doc/reference/sage/rings/real_mpfi.html
>
> -M. Hampton
>
> On Dec 9, 8:16 am, Laurent Claessens <moky.m...@gmail.com> wrote:
>
>
>
>
>
>
>
> > Hi
>
> > I would like to work with sets that are real intervals or combinations
> > of them : mainly intersection and union.
> > Example :
> > [0,1] intersection with [0.5 , pi]
>
> > Using the Sage Reference Manual 4.1.1, I was able to do that :
>
> > sage:A=Set(RealField())
> > sage: sqrt(2) in A
> > True
>
> > So it is possible to consider parts of R as sets. How can I build an
> > interval ?
>
> > Have a good day
> > Laurent Claessens
>
> > PS : I send this message by email on December, 4. Since I did not even
> > saw my message appearing, I decided to repost it from the GoogleGroup
> > online interface. I'm wrong in doing that ?
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