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MathGroup Archive 2000

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Re: insect population dynamics

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24629] Re: insect population dynamics
  • From: Mark Hunter <mhunter at sparc.ecology.uga.edu>
  • Date: Fri, 28 Jul 2000 17:24:11 -0400 (EDT)
  • Organization: @Home Network
  • References: <8lj8q0$8rr@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Thanks to all of those who replied to my request. I now have 3 different
ways of solving my problem, all of which work.

Much appreciated,

Mark

Mark Hunter wrote:
> 
> I'm trying to use mathematica to run insect population models.  I'm new
> to the system, and wolfram support suggested that I post my question
> here.
> 
> The models are simple predator-prey models.  They are non-linear
> simultaneous difference equations.  I've tried using RSolve, but it
> doesn't seem to handle the non-linearity.  Is there a way of using a
> Do-Loop for the same kind of thing?  A simple example of the model that
> I tried is:
> 
> RSolve[{a[n + 1] == a[n]*Exp[0.63((1 - a[n]/50)) - 0.068b[n]],
>       b[n + 1] = a[n]*(1 - Exp[-0.068*b[n]]), a[0] == 25,
>       b[0] == 10}, {a[n], b[n]}, n]
> 
> I want an output for variables a and n at time n, n+1, etc.
> 
> I'd be most grateful for any advice that you can offer, and please don't
> underestimate my current level of ignorance.
> 
> Many thanks,
> 
> Mark Hunter


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