I opened this issue a few days ago:
https://github.com/sympy/sympy/issues/9189
I bumped into this problem because it was raised by the stats module.
Apparently the integration algorithm is unable to cope with unions of
intervals.
I was wondering, is it correct to pass a union of intervals to th
Wow, I didn't know integrate supported Intervals. If we are going to
support sets, we might as well support all of them (at least
unevaluated). A union of intervals is easy if the values are
computable (i.e., if you can determine if the union is disjoint).
Otherwise, it's complicated. Integrate(1,
On Wednesday, March 25, 2015 at 5:29:18 PM UTC+1, Aaron Meurer wrote:
>
> Wow, I didn't know integrate supported Intervals.
I had a look at the code, I think that behaviour is unintended.
The point is, the stats module apparently calls *integrate* with intervals
to determine probabilities.
I
On Wed, Mar 25, 2015 at 1:21 PM, Francesco Bonazzi
wrote:
>
>
> On Wednesday, March 25, 2015 at 5:29:18 PM UTC+1, Aaron Meurer wrote:
>>
>> Wow, I didn't know integrate supported Intervals.
>
>
> I had a look at the code, I think that behaviour is unintended.
>
> The point is, the stats module app
Well, I was a bit surprised too, but the stats module apparently does so,
as shown in this example:
In [1]: from sympy.stats import *
In [2]: var('sigma', positive=True)
Out[2]: σ
In [3]: N = Normal('X', mu, sigma)
In [6]: P(N**2>1, evaluate=False)
Out[6]:
(-∞, -1) ∪ (1, ∞)
You don't need to square the random variable to compute the result. You
just need to integrate the pdf over x < -1 and x > 1
On Thu, Mar 26, 2015 at 5:42 AM, Francesco Bonazzi
wrote:
>
> Well, I was a bit surprised too, but the stats module apparently does so,
> as shown in this example:
>
> In
Matthew... what do you think of the union of intervals as an alternative to
the usual ranges in integrate/Integral?
I suppose that you wrote the code outputting that integral, which currently
does not work, and I want to make it work.
I am undecided on whether to edit sympy.stats in order to gi
I think integrating over sets is a useful thing to allow, but we
definitely need to be more careful about symbolic intervals. And given
that, it probably means that sympy.stats should just do normal
integrals, since it can make assumptions about symbolic intervals that
won't be present when passed
> Matthew... what do you think of the union of intervals as an alternative
to the usual ranges in integrate/Integral?
Seems like a decent plan. I haven't been actively working on stats in a
while so I don't have strong opinions here.
On Thu, Mar 26, 2015 at 6:50 PM, Aaron Meurer wrote:
> I t
