Re: Can someone tell me why NDsolve isn't working here?
- To: mathgroup at smc.vnet.net
- Subject: [mg44051] Re: Can someone tell me why NDsolve isn't working here?
- From: Alois Steindl <Alois.Steindl+e325 at tuwien.ac.at>
- Date: Sun, 19 Oct 2003 01:10:52 -0400 (EDT)
- References: <bmqplo$rhb$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Mizrandir schrieb: > Hello, Im trying to solve a system of 6 differential equations with > NDSolve but I can't get Mathematica to do it. I wrote: > > R = 1; > M = 1; > L = 1; > NDSolve[{Rx[t] + Fx[t] == 2M x''[t], Ry[t] + Fy[t] == 0, ^^^^^^^^^^^^^^^^^^^ This isn't a differential equation. Why do you think it is one? > Fx[t] R == -M R x''[t], -Rx[t] == ^ That starts a second equation for x''. Are you sure? >[...] > And Mathematica gave me the following error: > > NDSolve::"ndode": "Input is not an ordinary differential equation." > I agree. > Does anybody know what am I doing wrong. Can I use Mathematica to > solve this? > I have heard rumours that Mathematica 5.0 should be able to traet Differental-Algebraic equations. Alois