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[Mathematica] Bug in Integrate with derivatives of a delta function

  1. Jul 17, 2014 #1


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    Code (Text):

    Integrate[f[qs] DiracDelta'[qs (1 - 1/x)], {qs, -\[Infinity], \[Infinity]},
     Assumptions -> 0 < x < 1]
    Integrate[f[qs] DiracDelta'[qs - qs/x], {qs, -\[Infinity], \[Infinity]},
     Assumptions -> 0 < x < 1]
    This is on Mathematica 8 for windows.
    The results differ by a sign. They are effective the exact same thing, but due to how I write the insides of the dirac delta I get a different result.

    Can anyone replicate this?
    Last edited: Jul 17, 2014
  2. jcsd
  3. Jul 17, 2014 #2


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    Gold Member

    I notice it is only for the first negative power of x. If you put

    [qs (1 - 1/x^(1.))]

    [qs - qs/x^(1.)]

    it works?
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