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UnitStep Integration Rules

  • To: mathgroup at
  • Subject: [mg47668] UnitStep Integration Rules
  • From: "Reece, Daryl" <Daryl.Reece at>
  • Date: Tue, 20 Apr 2004 09:04:07 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

Can someone help me understand what is happening here.  UnitStep causes
problems with Integrate, so I wanted to write my own replacement rule and
skip the problem.

Integrate[UnitStep[t/Month - 5],t]/. {Integrate[UnitStep[t/Month - 5],t] ->
(t - 5 Month) UnitStep[(t - 5 Month)/Month]}


(t - 5 Month) UnitStep[(t - 5 Month)/Month]



Integrate[UnitStep[t/Month - 5],t]/. {Integrate[UnitStep[t/Month - m_],t] ->
(t - m Month) UnitStep[(t - m Month)/Month]}

yields the unevaluated integral.  I've also tried m__ and m___ along with
various versions of the rule derived from the FullForm expression of the
above integral.  Why can't Mathematica make the substitution with the blank
expression in the rule?


Daryl Reece


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