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[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 > > > >