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MathGroup Archive 2003

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Re: Defining function

  • To: mathgroup at
  • Subject: [mg44556] Re: Defining function
  • From: "Curt Fischer" <crf3 at>
  • Date: Fri, 14 Nov 2003 01:58:49 -0500 (EST)
  • References: <bovtvd$nbc$>
  • Sender: owner-wri-mathgroup at

"Ravinder Kumar B." <ravi at> wrote in message
news:bovtvd$nbc$1 at
> Dear All,
> How to define a function over two different ranges in mathematica.
> For example
> f(t):= Exp[-i*t]  for t > 0   and
>      = 0          for t < 0
> Your response/clarification will be deeply appreciated.

One possibility is to use If[], but you will probably be better off if you
use UnitStep[]:

f[t_] := UnitStep[t] Exp[-I t]
Plot[Re[f[t]], {t, 0, 10}, PlotRange -> {{-2 Pi, 2 Pi}, {-1, 1}}]

Doing calculus with Integrate[] and the like works much, much better if you
use UnitStep.


Curt Fischer

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