MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Integral of Piecewise function involving DiracDelta


Here is an integral that I expect Mathematica to evaluate to 1:

Integrate[Piecewise[{{DiracDelta[x], -1 < x < 1}}, 0],
  {x, -Infinity, Infinity}]

However, Mathematica 5.2 (Windows) gives the answer as 0. Here's a
similar integral that I also expect to evaluate to 1:

Integrate[Piecewise[{{DiracDelta[x-1/2], -1 < x < 1}}, 0],
  {x, -Infinity, Infinity}]

For this integral, Mathematica doesn't return 0. It returns the
following:

Integrate[Piecewise[{{2*DiracDelta[-1 + 2*x], -1 < x < 1}},
  0], {x, -Infinity, Infinity}]

Can anyone help me understand what's happening here?

Cheers,

Andrew



  • Prev by Date: Drawing a 3D representation of complex Fermat curve x^n + y^n = 1
  • Next by Date: Re: Timing in Mathematica
  • Previous by thread: Re: Drawing a 3D representation of complex Fermat curve x^n + y^n = 1
  • Next by thread: Re: Integral of Piecewise function involving DiracDelta