Defining the population control: foxes require hares

Revision as of 04:12, 14 September 2007 by ReneeB (Talk | contribs)

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1. Drag two variable nodes in the diagram. Type ‘Hares needed by 1 fox’ and ‘Foxes surviving’ for each node.

2. Draw arrow from ‘Hares needed by 1 fox’ to ‘Foxes surviving’, from ‘Hares captured’ to ‘Fox surviving’; and from ‘Foxes surviving’ to ‘Foxes at end’.

Foxes and Hares diagram 12.jpg

3. Double click on ‘Hares needed by 1 fox’ to open its object window. Click on the Identifier field, change it to ‘Hares_needed’. Press tab. In the Description field type ‘Number of hares that one fox must capture in a time period to survive.’

Object Hares needed.jpg

4. Double click on Foxes surviving to open its Object window. In the Description field type ‘Number of foxes surviving a time period, by eating the numbers of hares captured’. Press tab. In the Definition field type ‘Hares_captured/Hares_needed’.

Object Foxes surviving.jpg

5. Select Foxes at end. Click on the key icon to open the attribute panel. Click on the popup menu, select Definition. Type ‘Min([Foxes_surviving,Foxes_at_start])’

Foxes and Hares diagram 13.jpg

6. Select Populations, click on the result button.

Result Populations.1.1.jpg

7. Select Foxes at end, click on its key icon. Select Definition from the Attribute popup menu. Type ‘Max([2,Min([Foxes_surviving,Foxes_at_start])])’

Foxes and Hares diagram 14.jpg

8. Select Populations, click on the result button. A result window should appear.

Result Populations.1.2.jpg

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