[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-15 Thread rjf
I don't know how much verbiage to contribute to this notion of "returning infinity" being open to question. Just a few notes. When we say integrate from 0 to infinity, is "infinity" a value? Not really. We are asking about the computation of integration from 0 to Z where Z increases without

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-15 Thread rjf
On Sunday, March 12, 2017 at 4:38:41 AM UTC-7, Peleg Michaeli wrote: > > > you might simplify infinity-infinityto 0, > Well, this is the wrong thing here... but sage is smarter than that, I > believe. > > >>> I truly doubt that. There are presumably many subsystems that can make this

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-13 Thread kcrisman
As it happens, in this case the underlying problem is that we send such unevaluated integrals to GSL when asked for a numerical approximation, which can't handle this kind. Raising some kind of error or divergence notification makes more sense than returning infinity in any case. -- You

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-12 Thread Peleg Michaeli
> you might simplify infinity-infinityto 0, Well, this is the wrong thing here... but sage is smarter than that, I believe. On Saturday, 11 March 2017 19:09:07 UTC+2, rjf wrote: > > > > On Wednesday, March 1, 2017 at 2:11:41 AM UTC-8, Peleg Michaeli wrote: >> >> Hi, >> >> I have two questions,

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-11 Thread rjf
One other possibility for symbolic systems when the question when the object in question cannot be simplified or evaluated, is to return the unsimplified or unevaluated expression. The simplest case might be something like is (a>b) which, in the absence of any information about the values of

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-11 Thread rjf
On Wednesday, March 1, 2017 at 2:11:41 AM UTC-8, Peleg Michaeli wrote: > > Hi, > > I have two questions, one might be thought of as a bug report / feature > request, please tell me what you think. Trying > integrate(x, x, 0, infinity) > raises ValueError: Integral is divergent. > > My first

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-10 Thread Peleg Michaeli
Reported in https://trac.sagemath.org/ticket/22566 and in https://trac.sagemath.org/ticket/22567 On Thursday, 2 March 2017 11:56:05 UTC+2, Ralf Stephan wrote: > > Opening a ticket for bugs is always a good idea. > > On Wednesday, March 1, 2017 at 11:11:41 AM UTC+1, Peleg Michaeli wrote: >> >>

[sage-devel] Re: Integral is divergent (playing with floor and ceil)

2017-03-02 Thread Ralf Stephan
Opening a ticket for bugs is always a good idea. On Wednesday, March 1, 2017 at 11:11:41 AM UTC+1, Peleg Michaeli wrote: > > Hi, > > I have two questions, one might be thought of as a bug report / feature > request, please tell me what you think. Trying > integrate(x, x, 0, infinity) > raises