MathGroup Archive 2003

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  • To: mathgroup at
  • Subject: [mg43617] Bug!
  • From: Konstantin L Kouptsov <kouptsov at>
  • Date: Tue, 23 Sep 2003 04:02:44 -0400 (EDT)
  • Organization: Washington State University
  • Sender: owner-wri-mathgroup at

In version 5.0:

In[1]:= Integrate[Exp[-(x^2 + y^2)/2 - I (k x + l y)],
             {x,-Infinity,Infinity}, {y, -Infinity, Infinity}]

Out[1]:= (2*Pi)/E^((1/2)*(k^2 + l^2))

However, by adding S in the denominator one gets the wrong answer:

In[2]:= Integrate[Exp[-(x^2 + y^2)/2/S - I (k x + l y)],
             {x,-Infinity,Infinity}, {y, -Infinity, Infinity}]

Out[2]:= 0

The tail I (k x + l y) is important. Without it, Mathematica gives the
correct answer Sqrt[2*Pi*S].


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