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MathGroup Archive 2004

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Funny Behavior of InverseLaplaceTransform

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48007] Funny Behavior of InverseLaplaceTransform
  • From: "Husain Al-Mohssen" <husain at MIT.EDU>
  • Date: Wed, 5 May 2004 08:11:13 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Mathgroupers,

I don't know what to make of the following behavior of
InverseLaplaceTransform. To me it seems like a bug but I am not sure.

Start with this:
In[1]:=
InverseLaplaceTransform[Log[a (s + ce )]/s, s, t]

Out[1]=
-\[Infinity]

This looks a bit suspicious. Lets try re-writing it:

In[2]:=
PowerExpand[Log[a (s + ce)]/s]

Out[2]=
\!\(\(Log[a] + Log[s + ce]\)\/s\)

Let's Try it one more time:

In[3]:=
InverseLaplaceTransform[%,s,t]

Out[3]=
EulerGamma+Gamma[0,t ce]+Log[a]

Is this a bug or am I missing something here? I'd be very surprised if the
QC of Mathematica allowed a bug like this in the 5.0 kernel.

In[4]:=
$Version

Out[4]=
5.0 for Linux (November 18, 2003)


Yours,

Husain Al-Mohssen
Course 2 (Mechanical Engineering)




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