Re: Can someone tell me why NDsolve isn't working here?

*To*: mathgroup at smc.vnet.net*Subject*: [mg44066] Re: Can someone tell me why NDsolve isn't working here?*From*: mizrandir at hotmail.com (Mizrandir)*Date*: Mon, 20 Oct 2003 01:13:35 -0400 (EDT)*References*: <bmqplo$rhb$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I didn't know that Mathematica couldn't deal with systems of differential equations which included algebraic equations too (aren't algebraic equations a particular case of differential equations?). I've checked wolfram.com and it does say that Mathematica 5 can solve some DAEs, I think I will download the trial version and try it. miz. P.S.: Eckhard Hennig said: >looks to me like a mechanical system where >energy conservation is important Yes, it's a two-body dynamic system and energy conservation is important. In fact, to get an answer to the problem with generic mass (M), length (L) and radius (R), I think I'll have to solve it using energy consevation (but then I won't get the answer for a generic time (t)).