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once more integrate

  • To: mathgroup at
  • Subject: [mg20735] once more integrate
  • From: Wolfgang Schadow <schadow at>
  • Date: Wed, 10 Nov 1999 00:17:47 -0500
  • Sender: owner-wri-mathgroup at


here is one more integral that is not calculated correct:

In[4]:= Integrate[1/x^2,{x,-2,2}]

Out[4]= Infinity                    (correct)
In[5]:= Integrate[1/x^2,{x,-Abs[a],2}] /. a -> 2
Out[5]= -1                           (not correct)
In[6]:=  Integrate[1/x^2,{x,-Abs[a],2}]
          1      1
Out[6]= -(-) - ------
          2    Abs[a]  
In[7]:=  Integrate[1/x^2,{x,-a,a}]
Integrate::idiv: Integral of x   does not converge on {-a, a}.
Out[7]= Integrate[x  , {x, -a, a}]
In the first case Mathematica gives the corrcet answer, in the
second case it overlooks the singularity. In the third case the
answer is at least not wrong.

Wolfgang Schadow

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