Re: NDSolve with functions of vectors

*To*: mathgroup at smc.vnet.net*Subject*: [mg82977] Re: NDSolve with functions of vectors*From*: John Lee <johnlee_15 at hotmail.com>*Date*: Mon, 5 Nov 2007 05:07:13 -0500 (EST)

I'm trying to keep a specific form because this is meant to be a sort of tutorial for students who have never used Mathematica. That's why I'd like to figure out why what I did is not working. I defined a[0]==X, so if X={1,1,1}, then shouldn't Mathematica recognize a[s] as having 3 components? When I tried U[a[s]] within NDSolve, it keeps giving me an error saying that a[s] only has 1 component. I've tried U[a[s][[1]],a[s][[2]],a[s][[3]]] and Mathematica tells me that the second and third components of a[s] do not exist. Is what I'm saying making any sense? It's hard to explain.