       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 == 25,
>       b == 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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