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MathGroup Archive 1997

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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 


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