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Re: NDSolve with delayed terms in equations

• To: mathgroup@smc.vnet.net
• Subject: [mg11891] Re: NDSolve with delayed terms in equations
• From: Bill Bertram <wkb@ansto.gov.au>
• Date: Fri, 3 Apr 1998 03:45:46 -0500
• Organization: ANSTO
• References: <6fsj92$gi8@smc.vnet.net>

Alban P Tsui wrote:
> 
> I have a set of differential equations. Usually I can solve it with
> NDSolve with no problem. However, I do not know how to solve something
> like this, say
> 
> x'[t]==y[t]^2+x[t-a]
> y'[t]==y[t]x[t]
> 
> with the usuaual intial conditions and a is real and positive.
> 
> x[t-a] is a delayed term.
> 
> What is the best way to tackle this with NDSolve?
> 
> Alban
> P.S. Appreciate if you can send solution to me directly as well.

While browsing MathSource at the Mathematica web site (www.wolfram.com)
today, I happened come across a package that may be what you're after. 
The package for Mathematica version 3.x is NDelayDSolve.m and can be
found in MathSource as Enhancements/Numerical/0209-102.

I hope this is useful to you.
Cheers,
   Bill