Defining hare population as a function of time

• On the diagram, click on 'Hares at start' node to select it. Click on the key icon to open the Attribute panel. Click on the Description field, type ‘The hare population at the start of each time period.’ Press Alt+Enter.

• Select Definition from the Attribute dropdown menu. Click on the expr popup menu, select ‘other’. Object finder window should appear.

• Select ‘Special’ from the Library popup menu, subsection control constructs and local variables.

• Select Dynamic to open parameter box for Dynamic function(). Click on the Dynamic field. Type without quotes ‘100, Hares_at_end[Time-1]*(1+Hare_birth_rate)’. Click OK button.

Expected: You should have this result. Note in particular, the gray arrow pointing from Hares at end to Hares at start.

• Select ‘Hares at end’. Select ‘Description’ from the Attribute popup menu. Type ‘The hare population at the end of each time period.’

• Select ‘Definition’ from the Attribute popup menu. Click on the definition field.

Expected: Inputs popup menu should appear.

• Click on the inputs popup menu, and select ‘Hares at start’.

• Click on the ‘Show result’ button on the tool palette.

Expected: A result table window should appear. Change to graph

See Also

• Tutorial: Dynamic system model
• Creating the Foxes and Hares model (based on chapter 7 of tutorial)