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