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