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MathGroup Archive 2005

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DSolve and K$31, i am puzzled

  • To: mathgroup at
  • Subject: [mg57078] DSolve and K$31, i am puzzled
  • From: David Boily <dsboily at>
  • Date: Sat, 14 May 2005 04:58:23 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

When i try to solve this differential equation with the command:

In[1]:= DSolve[f'[t] == Sign[p2 Exp[F2 t] - p1 Exp[F1 t] + p], f[t], t]

where p, p1, p2, F1 and F2 are constants i get the answer

                        F1 t       F2 t
                  (p - E     p1 + E     p2) (-K$31 + t)
Out[1]= {{f[t] -> ------------------------------------- + C[1]}}
                               F1 t       F2 t    2
                    Sqrt[(p - E     p1 + E     p2) ]

what the hell is K$31? I have tried to find out with google or
the mathematica 5 online docs but have found nothing.

can someone enlighten me?

David Boily
Centre for Intelligent Machines
McGill University
Montreal, Quebec

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