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Constant function Integrate Assumption - More

• To: mathgroup at smc.vnet.net
• Subject: [mg47252] Constant function Integrate Assumption - More
• From: "Reece, Daryl" <Daryl.Reece at goody.com>
• Date: Thu, 1 Apr 2004 00:03:41 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Many thanks to everyone offering solutions to my dilemma.  In trying to
simplify the problem, I must have slipped up and oversimplified.

Specifically I want to start with

Integrate[50000 Units/Year UnitStep[(t-5 Month)/Month], t]

and receive

50000 Units/Year (t-5 Month) UnitStep[(t-5 Month)/Month].

I need the full answer so that the units work out correctly in the answer.
I am starting with a sale rate and want to derive the total sales as a
function of time.  This time may then be input as Days, Months, Years....
If I perform the replace operation, as many of you suggest, this ability
disappears.

A lister rightly pointed out that Mathematica is confused not because it
assumes that Month may be a function of t, but rather it does not know the
sign of Month.  Even using the assumption Month>0 does not fix the problem.

Other suggestions?

• Follow-Ups:
  • Re: Constant function Integrate Assumption - More
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>