WOLFRAM SYSTEMMODELER

Hair_Lynx_Interaction

Predator/prey model

Diagram

Wolfram Language

In[1]:=
Click for copyable input
SystemModel["SystemDynamics.IntroductoryExamples.Hair_Lynx_Interaction"]
Out[1]:=

Information

The hare/lynx interaction model is a typical two-species predator/prey model. This example has been borrowed from SystemDynamics 1.0. The original version of this example can be found in the STELLA tutorial.


References:

  1. Richmond, B., S. Peterson, and P. Vescuso (1987), An Academic User's Guide to STELLA, High Performance Systems, Inc., Lyme, N.H.


Simulate the model across 60 time units and plot the two animal populations against simulation time:

You need to reduce the accuracy to 1e-10 in order for the simulation to run correctly.

Also plot the two population against each other:

You shall notice that the limit cycle is mildly unstable.

The simulation results obtained are not exactly the same as with SystemDynamics 1.0. The reason is that the previous version used tabular interpolation functions with linear extrapolation, whereas the new version uses tabular interpolation functions without extrapolation capability (a more prudent approach). In line with STELLA philosophy, the support values of the two tabular functions were manually extended to reflect a constant rather than a linear extrapolation.

Outputs (2)

hare

Type: Real

Description: Hare population

lynx

Type: Real

Description: Lynx population

Components (18)

Hare

Type: Level

Hare_Birth

Type: Rate_1

hare_birth_factor

Type: Gain

Source1

Type: Source

hare_density

Type: Gain

Hares_Killed_Per_Lynx

Type: Tabular

Hare_Death

Type: Rate_1

Sink1

Type: Sink

Lynx

Type: Level

Lynx_Birth

Type: Rate_1

lynx_birth_factor

Type: Gain

Source2

Type: Source

Lynx_Death

Type: Rate_2

prod_2_1

Type: Prod_2

Lynx_Death_Fraction

Type: Tabular

Sink2

Type: Sink

Hunting

Type: Pulse

prod_2_2

Type: Prod_2