       Re: DSolve

• To: mathgroup at smc.vnet.net
• Subject: [mg18819] Re: [mg18738] DSolve
• From: "Alex Scheitlin" <alex-s at worldnet.att.net>
• Date: Thu, 22 Jul 1999 08:19:33 -0400
• Organization: AT&T WorldNet Services
• References: <7n13nc\$bf5@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Tried it V4 it didn't work.

For the fun of it I tried NDSolve and got following message

NDSolve::"ndv": "For a boundary value problem, only nth order single linear
\
ordinary differential equations is supported."

Richard Finley <rfinley at medicine.umsmed.edu> wrote in message
news:7n13nc\$bf5 at smc.vnet.net...
> 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==2,
>                 v==0,v''==0,v==0,v''==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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