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MathGroup Archive 2007

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RE: question (for Mathematica 6!)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75544] RE: [mg75519] question (for Mathematica 6!)
  • From: "Owen, HL \(Hywel\)" <h.l.owen at dl.ac.uk>
  • Date: Sat, 5 May 2007 05:52:15 -0400 (EDT)

HeavisideTheta[0] is undefined
UnitStep[0] gives 1

Their integrals are the same (for example from -1 to 1).

And:
D[HeavisideTheta[x], x] is DiracDelta[x]
Whereas
D[UnitStep[x], x] is (-1 - DiscreteDelta[x] + UnitStep[-x] +
UnitStep[x])/(1 - 
 DiscreteDelta[x])

Hywel 

> -----Original Message-----
> From: dimitris [mailto:dimmechan at yahoo.com] 
> Sent: Friday, May 04, 2007 9:09 AM
> To: mathgroup at smc.vnet.net
> Subject: [mg75519] question (for Mathematica 6!)
> 
> I don't have a copy of Mathematica 6 but having spent much 
> time reading the online documentation (not only because of 
> curiosity!) I have one question...
> 
> Can somebody explain me the introduction of the 
> HeavisideTheta function
> 
> http://reference.wolfram.com/mathematica/ref/HeavisideTheta.html
> 
> in version 6?
> 
> Note that the UnitStep function is still here
> 
> http://reference.wolfram.com/mathematica/ref/UnitStep.html
> 
> Dimitris
> 
> 
> 
> 



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