Virtual Laboratory Environment

Version 2.0.2

A Modeling & Simulation Environment

video: Forrester diagrams

Lotka Volterra equation with Forrester diagrams

We used the gvle.forrester package to model the Lotka Volterra equations into the Ordinary Differential Equations (package vle.ode)

Video Comments:

  • 0:00 : Create the package lotkavolterra and specify a dependency to the vle.ode package.
  • 0:18 : Create a new atomic model based on the Forrester formalism. By default, its name is NewCpp.
  • 0:24 : Define two compartments x and y and give their initial values.
  • 0:46 : Define four parameters alpha, beta, gamma and delta and give their values.
  • 1:36 : Define two material flows flowX and flowY.
  • 1:53 : Declare a hard link from flows to compartments.
  • 1:59 : Declare dependencies between flows and parameters.
  • 2:23 : Give equations of the flows (depending on compartments and parameters).
  • 3:06 : Modify the time step to 0.01, for the Euler method, of the numerical integration.
  • 3:22 : Close the atomic model description and rename it to LotkaVolterra.
  • 3:24 : Configure and build the project.
  • 3:44 : Open the default model empty.vpz and add an atomic model, configure it with the newly created dynamic LotkaVolterra from package lotkavolterra.
  • 3:56 : Into the Observables tab, attach the observable ports to the available view of the vpz.
  • 4:11 : Save file and select the Simulation tab to launch simulation.
  • 4:18 : Change the duration of simulation, re-launch simulation, and plot the compartments x and y.
Last updated on 29 Nov 2018, 15:39
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