once more integrate

• To: mathgroup at smc.vnet.net
• Subject: [mg20735] once more integrate
• Date: Wed, 10 Nov 1999 00:17:47 -0500
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

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}]

-2
Integrate::idiv: Integral of x   does not converge on {-a, a}.

-2
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             Phone: +1-604-222-1047 ext. 6453 (office)
TRIUMF                              +1-604-875-6066           (home)
Theory Group                   FAX: +1-604-222-1074
4004 Wesbrook Mall
Vancouver, B.C. V6T 2A3      email: schadow at triumf.ca