MathGroup Archive 2004

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

Search the Archive

Re: NDSolve and time-delayed equations?


Gareth Russell wrote:
> Hi,
> 
> Can NDSolve be used to approximate the dynamics of continuous but
> time-delayed equations? Here is an example of the standard continuous
> logistic model used in ecology:
> 
> NDSolve[{n'[t] == 0.5*n[t]*(1 - n[t]/100), n[0] == 10}, n, {t, 0, 20}]
> 
> It does, of course, have an analytical solution.
> 
> A time-delayed version would make the derivative a function of two
> values: n'[t,t-lag], but I can't figure out if a formulation like this
> is possible. The key thing seems to be that while the derivative of n
> is a simple function of two parameters, n itself is not.
> 
> Any suggestions, other than iterating as a discrete-time model with
> very small time-steps?

Check out the NDelayDSolve package by Allan Hayes.  

http://library.wolfram.com/infocenter/MathSource/725/

I've used it to solve delay equations.

-- 
Curt Fischer


  • Prev by Date: Re: simple bug about Sum/Product function?
  • Next by Date: Converting to Standard LaTeX
  • Previous by thread: NDSolve and time-delayed equations?
  • Next by thread: Re: NDSolve and time-delayed equations?