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Re: Problem with Differential Eq

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82587] Re: Problem with Differential Eq
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 25 Oct 2007 06:12:13 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <ffn068$5m2$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

you miss a comma

solution =
   NDSolve[{lpmk1'[
       t] == (lpmk10[lpv[t]] - lpmk1[t])*(1/lptaumk1[lpv[t]]),
     lpmk1[0] == lpmk10[-80]*(1/lptaumk1[-80]),
     lpv'[t] == -1*(+1*125*(lpmk1[t] 4)*(lpv[t] + 80)),
     lpv[0] == -80}, {lpv, lpmk1}, {t, 0, 1500}, Method -> Automatic];
ParametricPlot[Evaluate[{t, lpv[t]} /. solution], {t, 0, 1500},
  PlotPoints -> 1500, PlotRange -> All]

may work.

Regards
   Jens


Dave wrote:
> The following .nb file just won't run!!! I can't see what is wrong as it is 
> a relativly simple series of self evaluating differential equations.
> 
> [code]
> 
> lpmk10[u_] := 1/(1 + Exp[(u + 12.3)/-11.8]);
> lptaumk1[u_] := 14.4 - 12.8/(1 + Exp[(u + 28.3)/-19.2]);
> 
> solution =
> NDSolve[{lpmk1'[t] == (lpmk10[lpv[t]] - lpmk1[t])*(1/lptaumk1[lpv[t]]),
> lpmk1[0] == lpmk10[-80]*(1/lptaumk1[-80])
> lpv'[t] ==
> -1*(+1*125*(lpmk1[t]^4)*(lpv[t] + 80)),
> lpv[0] == -80},
> {lpv, lpmk1}, {t, 0, 1500}, Method -> Automatic];
> ParametricPlot[Evaluate[{t, lpv[t]} /. solution], {t, 0, 1500},
> PlotPoints -> 1500, PlotRange -> All];
> 
> 
> 
> [/code]
> 
> 
> 
> if any one can shed some light on this it would be great
> 
> 
> 


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