REPLY First order oscillation (SD6465)

[SDMAIL Welch, Cory]

Posted by  "Welch, Cory" <Cory_Welch at nrel.gov>

All,

Thank you all for your responses. Sterman's response cleared it up for
me entirely. My original posting should have read that oscillation is
impossible in a first-order "differential" rather than "difference"
equation. 

I'd still question, however, whether a "difference" formulation should
be used to model ecological systems. It seems there are many papers out
there pointing to difference formulations as an explanation for
oscillation and/or chaotic behavior in natural systems. Rather, it seems
to me that a continuous time formulation would be more appropriate,
modeling any non-continuous type behavior (e.g., seasonal mating, etc.)
with an appropriate order delay to study its affect on the dynamics. 

All my best,

Cory


Cory J. Welch
Senior Energy Analyst
National Renewable Energy Laboratory
Strategic Energy Analysis and Applications Center
Posted by  "Welch, Cory" <Cory_Welch at nrel.gov>
posting date  Sat, 2 Jun 2007 14:47:26 -0600