Bug in NDSolve MMA 2.2 for PC

*To*: mathgroup at smc.vnet.net*Subject*: [mg6968] Bug in NDSolve MMA 2.2 for PC*From*: Edgar Camacho Cota <ecc at ds5000.super.unam.mx>*Date*: Wed, 30 Apr 1997 22:25:42 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On Thu, 24 Apr 1997, Hong-liang Xie wrote: > In article <5jn11v$b11 at smc.vnet.net> you wrote: > > > : I want to solve a system of ODE's for the functions q[1][t], q[2][t], > : ... etc, then I try : > : NDSolve[{system....}, {q[1][t], q[2][t], q[3][t],...}, t] > > : this work well if the system is small, but if the system is great, > : this not work, and appear the message: the system not evaluate to a > : number in ..<the first value for t> > > : the problem can be solved if I replace the q[1][t] for q1[t] and then: > : NDSolve[{system with q1[t], q2[t]....}, {q1[t],q2[t],..}, t] > > : Why ?? what's happen? > > I wonder if you are trying a similar problem as mine. As I posted, > I need to solve recurrence equation of form: > > u[x,y] = 2 u[x,y+1] + 3 u[x+1,y] (1 <= x <= 5, 1 <= y <= 4) > > Your problem appears similar to a novice as I, do you think that > by any chance I can NDSolve to solve my problem? I look up NDSolve > and found it not applicable, though. > > Thanks for your help. I am just a bit desperate. > > Hong > if you want to solve a ddiference equations by NDSolve you need rewrite your equation like a diferential equations and then apply NDSolve. my problem is different.are there a bug in mathematica ? I don't know..... mmmmmmm