       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[t], q[t],
> : ... etc, then I try :
> : NDSolve[{system....}, {q[t], q[t], q[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[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

```

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