Re: [RE] Can someone tell me why NDsolve isn't working here?
- To: mathgroup at smc.vnet.net
- Subject: [mg45325] Re: [RE] Can someone tell me why NDsolve isn't working here?
- From: Ed Nowak <ewnowak at mfire.com>
- Date: Tue, 30 Dec 2003 04:14:31 -0500 (EST)
- References: <bsjl8s$23u$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi Miz, Could you give the corrected system of 6 DAE equations, initial conditions, and parameter values? I am curious to see if Mathematica 5 will solve the problem as originally stated. Thanks, Ed. Mizrandir wrote: > A month or so ago I posted a problem I had with a system of 6 > algebraic-differential equations. In case someone is interested, I did > solve the problem. > > First of all, the equations had some minor mistakes (a wrong sign, a > missing constant...). After correcting those I simplified within them > until I was left with only these two equations: > > x''[t] = L * (\[Theta][t]^2 * Sin[\[Theta][t]] - \[Theta]''[t] * > Cos[\[Theta][t]]) / 8 > \[Theta]''[t] = 3 * (g * Sin[\[Theta][t]] - x''[t] * Cos[\[Theta][t]]) > / 2 / L > > This two equations can be simplified even more (by substitution of > the first one into the second one) to get one diferential equation (of > \[Theta][t]). After giving a numeric value to L and g, I soved it with > NDSolve and with the \[Theta][t] function it gave me, I solved for > x[t] too. I didn't solve for Rx, Ry, Fx and Fy because I wasn't > interested in them (they were only needed to set up the equations). > > miz. >