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MathGroup Archive 1999

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Re: DSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg18757] Re: [mg18738] DSolve
  • From: BobHanlon at aol.com
  • Date: Tue, 20 Jul 1999 01:33:22 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

On version 4 for a Power Macintosh the DSolve returned unevaluated after a 
few seconds.

I also verified your stated solution and boundary values as valid.

Bob Hanlon

In a message dated 7/17/99 5:28:17 AM, shamsundar at uh.edu writes:

>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.
>


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