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.

## Advertising

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 gives 0. I think it makes sense, both mathematically and from a practical point of view, to always make integrals over zero-measure domains equal to 0. Aaron Meurer On Fri, Feb 2, 2018 at 6:26 PM, Chris Smith <smi...@gmail.com> wrote: > 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 condition depends on x and y whereas in the 2nd > case it only > depends on y...and in the first case since it depends on x and x's range for > the 2nd expression > is from 3 to 3 (zero width) it can't contribute to the integration. So is it > right to ignore the value > of y? > > And what if there were a DiracDelta function there instead of 2 and the > integration went to 4 instead > of 3...then there *would* be a contribution...but this is presently ignored > by the current routine: > > ``` >>>> integrate( Piecewise((DiracDelta(x),x<2),(0,True)), (x,-1,1)) > 1 >>>> integrate( Piecewise((DiracDelta(x),Eq(x,0)),(0,True)), (x,-1,1)) > 0 > ``` > > /c > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/f0588adf-0e7f-44fd-b880-d60795f5424c%40googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6KBUXoU7FyP3GWLe%3DROAVKXbk5ybNXAD6dY7-QSoyBwWQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.