Problem with CHasing[]
- To: mathgroup at smc.vnet.net
- Subject: [mg17946] Problem with CHasing[]
- From: Andreas Stahel <Andreas.Stahel at hta-bi.bfh.ch>
- Date: Sat, 5 Jun 1999 02:56:10 -0400
- Organization: S.u.S.E GmbH, Gebhardtstr. 2, 90762 Fuerth, Germany
- Sender: owner-wri-mathgroup at wolfram.com
To whom it may concern
I need a package to solve two point boundary value problems.
A while ago I found the package Chasing.m on mathsource and liked what I
saw. Simple to use in simple situations. Unfortunately I came across a
false solution for a very simple problem.
I suspect numerical problems as the reason for the incorrect answer,
as the RHS of the boundary value problem is variing rapidly.
With best regards
Andreas Stahel
--
Andreas Stahel, Mathematics, HTA, CH-2501 Biel, Switzerland
Andreas.Stahel at hta-bi.bfh.ch
Tel 41--32--32 16 258 FAX: 41--32--32 16 500
here is the code leading to a false result.
=========================================================
Clear[f,L,u,un]
f[x_] = Exp[-((x-1.5)/0.3)^2];
L=3;
un[x_] =u[x]/.
Chasing[{D[u[x],{x,4}]==f[x],
u[0]==0,u'[0]==0,u[L]==0,u'[L]==0},u[x],{x,0,L}];
Plot[{f[x],un[x]},{x,0,L},PlotRange ->All];
un'[0]
--
Andreas Stahel, Mathematics, HTA, CH-2501 Biel, Switzerland
Andreas.Stahel at hta-bi.bfh.ch
Tel 41--32--32 16 258 FAX: 41--32--32 16 500