Re: [sympy] does this Piecewise integration look right?

2018-02-13 Thread Boris Ettinger
I agree with Leonid, there is no consistent way to define integral [0,anything) of the delta function. It is a theorem, in fact. Aaron, Sympy seniors, What was the reasoning to define DiracDelta as a function? How difficult would it be to insert GeneralizedFunction class above the Function class

Re: [sympy] does this Piecewise integration look right?

2018-02-02 Thread Leonid Kovalev
By definition (e.g., https://en.wikipedia.org/wiki/Dirac_delta_function#As_a_measure), DiracDelta would have integral one over any set that contains 0, even if that set has only one point. So one has to ask, when we integrate over (x, a, b), do we mean closed interval [a, b], open (a, b), or half-o

Re: [sympy] does this Piecewise integration look right?

2018-02-02 Thread Aaron Meurer
The condition is an And, so it requires both to be true. Thus, it is only 2 at one value, x=3, which means it doesn't contribute to the integral. I'm not really sure how to interpret the Dirac Delta integral. It seems to me that it should be the same as integrate(DiracDelta(x), (x, 0, 0)), which g

[sympy] does this Piecewise integration look right?

2018-02-02 Thread Chris Smith
I'm also wondering if the following behavior is right: ``` >>> Piecewise((1, x < 1), (2, Eq(x, 3) & (y < x)), (3, True)).integrate((x, 0, 3)) 7 >>> Piecewise((1, x < 1), (2, y < 3), (3, True)).integrate((x, 0, 3)) Piecewise((5, (y >= -oo) & (y < 3)), (7, True)) ``` In the first case, the 2nd con