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MathGroup Archive 1999

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Re: DSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg18781] Re: [mg18738] DSolve
  • From: "Richard Finley" <rfinley at medicine.umsmed.edu>
  • Date: Tue, 20 Jul 1999 01:33:35 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

I tried it in version 4.....also no success.  RF

>>> N. Shamsundar <shamsundar at uh.edu> 07/17/99 12:36AM >>>
Here is a pair of differential equations that Version 3 could not solve
(actually, it was still trying after 15 minutes on a 400 MHz PII!)

w:=Exp[-a x];
DSolve[{u'[x]==-u[x]+v[x]+w  (1-a)+Cos[Pi x]-(1+Pi) Sin[Pi x],
		v''''[x]==u[x]+v[x]+(Pi^4-1) Sin[Pi x]-Cos[Pi x]-w, u[0]==2,
                v[0]==0,v''[0]==0,v[1]==0,v''[1]==0},
                {u[x],v[x]},x]

These are linear equations with constant coefficients, and the exact solution
is
	u=w+cos(Pi x), v=sin(Pi x)

I would appreciate someone running this calculation in Version 4.

N. Shamsundar
University of Houston





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