MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: NDSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg42904] Re: NDSolve
  • From: "Kevin J. McCann" <kjm@KevinMcCann>
  • Date: Sat, 2 Aug 2003 04:12:28 -0400 (EDT)
  • References: <bgctse$9l9$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Are k1, k2, km1, km2,M specified? It is difficult to reproduce results
without all the information.

Kevin

"Steffen" <nnnx at gmx.de> wrote in message news:bgctse$9l9$1 at smc.vnet.net...
> Hi all,
> unfortunately Mathematica is not able to solve the following:
>
> NDSolve[{
>
> y1'[x] == -k1 y1[x] y2[x] + km1 y3[x],
>
> y2'[x] == -k1 y1[x] y2[x] + km1 y3[x],
>
> y3'[x] == k1 y1[x] y2[x] + km2 y4[x] M - (km1 + k2 M) y3[x],
>
> y4'[x] == -km2 M y4[x] + k2 M y3[x],
>
> y1[0] = 10^13,
>
> y2[0] = 10^16,
>
> y3[0] = 0,
>
> y4[0] = 0,
>
> } , {y1 , y2 , y3 , y4} , {x , 0 , 50 10^-6}]
>
>
>
> This is a differential equation system for a kinetical system ( y1 + y2
<=>
> y3 ,  y3 <=> y4). Only y1 and y2 exsists in the beginning. The constants
k1,
> km1, k2, km2 and M are numbers and are defined above.
>
> Mathematica gives an error: " NDSolve::ndnef : The number of differential
> equations (3) is not equal to the number of the initial conditions (1)."
>
> But I did gave him all the initial conditions, did´nt I? By the way there
> are 4 eq. and 4 conditions.
>
> I am sorry for this probably easy prob. I looked in Mathematica Help, in
> this forum and at Wolframs MathSource Webpage. I did not find anything for
> helping me to solve this Prob. This means, that I am making a very stupid
> mistake, but I do not know, which one. Can please anybody help me?
>
> Thanks a lot
>
> Steffen Nasterlack
>
> University of Karlsruhe
>
> Germany
>
>
>



  • Prev by Date: Re: Severe ToExpression Fault?
  • Next by Date: Re: NDSolve
  • Previous by thread: Re: NDSolve
  • Next by thread: Re: NDSolve