I have found that while these two should be the same, mathematica does not evaluate them equally.(adsbygoogle = window.adsbygoogle || []).push({});

I believe the second one is correct.Code (Text):Integrate[(a + b el + c el^2) DiracDelta[u], {u, 0, 1}, {el, e1, e2}]

Integrate[ Integrate[(a + b el + c el^2) DiracDelta[u], {el, e1, e2}], {u, 0, 1}]

Also please try :

Notice its just a simple sum of terms, but the last two are zero while the first is not. As soon as you include the first variable in the integrand, it doesn't seem to work.Code (Text):Integrate[(1 + u) DiracDelta[u], {u, 0, 1}, {el, e1, e2}]

Integrate[(el) DiracDelta[u], {u, 0, 1}, {el, e1, e2}]

Integrate[(1 + u + el) DiracDelta[u], {u, 0, 1}, {el, e1, e2}]

If you change the region of the u integration to -1..1, then its fine.

Does Mathematica have a problem with evaluating delta's on when the function sits on the boundary of integration? I assumed it would just use the definition of:

Code (Text):Integrate[ DiracDelta[u], {u, -1, 1}]

Integrate[ DiracDelta[u], {u, 0, 1}]

Any ideas? This is Mathematica 7 for Ubuntu.

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# Mathematica Bug : Integrate and DiracDelta

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