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Bug in Mathematica 4.1?

  • To: mathgroup at
  • Subject: [mg29231] Bug in Mathematica 4.1?
  • From: Daniel Arteaga <darteaga at>
  • Date: Wed, 6 Jun 2001 04:24:19 -0400 (EDT)
  • Sender: owner-wri-mathgroup at


Mathematica solves the differential equation 

 x y''[x] + (x+1) y'[x] + (1 + r) y[x] == 0

giving two solutions of the equation, one in terms of Laguerre
polinomials, and the other in terms of an hypergeometric function. But
if you previously specify previously the value of r, let's say r=1, and
also the corresponding bundary or ninitial conditions, then Mathematica
4.1 starts running forever, and does not give any solution. This
behaviour is not present on Mathematica 4.0.

I suspect that this is due to the fact that both solutions provided by
Mathematica are not independent when r>0. The hypergeometric solution is
a constant multiplied by the other solution. Mathematica 4.0 provided
different solutions of the diff. eq., so that there was no problem.


Daniel Arteaga

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