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RE: Integrate: A feature or a bug?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg34272] RE: [mg34248] Integrate: A feature or a bug?
  • From: "DrBob" <majort at cox-internet.com>
  • Date: Mon, 13 May 2002 05:54:16 -0400 (EDT)
  • Reply-to: <drbob at bigfoot.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Your answers are correct... you need to upgrade!

Bobby

-----Original Message-----
From: Vladimir Bondarenko [mailto:vvb at mail.strace.net] 
To: mathgroup at smc.vnet.net
Subject: [mg34272] [mg34248] Integrate: A feature or a bug?

Hello,

I have a fairly old version of Mathematica.

It produces

In[1] := Integrate[Integrate[Integrate[Integrate[1/(4 - (x + y + z +
w)),
         {x, 1, 2}], {y, 1, 2}], {z, 1, 2}], {w, 1, 2}]


Out[1] = Integrate[Integrate[Integrate[If[w + y + z < 2 || Im[w + y + z]
!= 0 ||
         w + y + z > 4 && w + y + z > 4, Log[(-3 + w + y + z)/(-4 + w +
y + z)] -
         Log[(-2 + w + y + z)/(-4 + w + y + z)], Integrate[(4 - w - x -
y - z)^(-1), {x, 1, 2},
         Assumptions -> Im[w + y + z] == 0 && w + y + z >= 2 && w + y +
z <= 4]], {y, 1, 2}],
         {z, 1, 2}], {w, 1, 2}]

Is is a feature or a bug?
Can anybody interpret the output?


My idea, the answer is

((-176*Log[2])/3 + 36*Log[3])/2

-0.557296


New version 4.1 produces

NIntegrate[Integrate[Integrate[Integrate[1/(4 - (x + y + z + w)),
          {x, 1, 2}], {y, 1, 2}], {z, 1, 2}], {w, 1, 2}]

-0.557296


Thank you in advance.


Vladimir Bondarenko







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