Popdyn - manual
PopDyn 2.01en.
Freeware from www.jonax.se
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Content.
1. System requirements.
1.1. Recommended system.
1.2. Minimum system.
2. Basic features.
2.1. Introduction.
2.2. The food-chain.
2.3. The state of the cells.
2.4. Killing or adding (human interference).
2.5. Iterations.
2.6. Graphs and autosave.
2.7. Files for saving the state of the simulation.
3. Advanced feature.
3.1. Digestion-efficency.
4. Appendix.
Screenshot and explanations.
1. System requirements.
1.1. Recommended system.
Windows 2000/XP
Screen resolution: 1024x768 or bigger
Processor: 2 GHz or faster
1.2. Minimum system.
Windows 95/98/ME/2000/XP/VISTA
Screen resolution: 1024x768 or bigger
Processor: 800 MHz
2. Basic features.
2.1. Introduction.
Popdyn is a simulation of a small eco-system with a four level food-chain. A benign sun is shining on the groving vegetation. Cells move forward at a constant speed; eating, starving or being eaten. They bounce at the walls. They never change course for hunting or to avoid being eaten. If the cells manage to get enough food they divide in two. If not they soon starve to death. The dynamics of the system can be affected by setting the Digestion-efficiency parameters.
2.2. The food-chain.
The vegetation is growing at a constant rate until it's full-grown. The vegetation can shrink but it never dies.
The herbivores graze the vegetation.
The red carnivores eat the blue herbivores.
The yellow top-predators eat the red cells. These top-predators also kill any weaker rivals encountered.
2.3. The state of the cells.
Darker shades means that the units contain more biomass.
When the cells reach the maximum level they divide in two.
If they can't find enough food they eventually starve to death.
2.4. Killing or adding (human interference).
You can interfere directly in this simulation if it pleases you.
Click on any cell you may wish to kill.
Add more cells by draging-and-droping. Use the right mouse button.
Start the dragging from the boxes.
(There are limits to the total number of cells.)
2.5. Iterations.
The system iterates (i.e. the vegetation grows and the cells move, etc.) a few times per second depending on setting.
Every tenth iteration the numbers of cells and the biomass of the vegetation are recorded on the graph.
Every k (thousand iterations) the 10k-graph (accessible by choosing Tools - Graph in the menu) is updated.
2.6. Graphs and autosave.
Autosave OFF.
Autosave ON.
(Example of a saved 10k-graph)
Autosave mode means that the graph will be saved as bmp-file every 10th k. The files will be named:
pd000010.bmp
pd000020.bmp
pd000030.bmp
...
etc, ad infinitum.
Existing files with the same names will be overwritten without further warnings. Place the graphs in some other directory -or rename them before re-starting, if you want to save the results of the simulation.
2.7. Files for saving the state of the simulation.
The following files are used for saving data about the current simulation.
acar.dat
agen.dat
aher.dat
apre.dat
agraf.bmp
Don't mess with those files.
3. Advanced feature.
3.1. Digestion-efficency.
Digestion efficiency, D.E. is the percentage of eaten biomass that is assimilated by the cells. The D.E. can be changed (by choosing Tools - Parameters in the menu) for each type of cell. Changeing those parameters will affect the dynamics of the system. Some combinations may lead to extinction of some or all cells.
It's suggested not to put emphasis on the absolute numbers of the D.E. The mathematically inclined user should be aware that the burn-rate and maximum biomass differs between the different cell-types.
4. Appendix.
Full-size screenshot with some explanations.
A - Digestion efficencies for blue : red : yellow cells.
B - Choose system-speed here: slow, normal or fast.
C - Autosave mode indicator.
D - The number of thousand iterations that has occurred.
E - The percentage of the total number of red and dead that have died by starvation.
F - Indicates the biomass of the vegetation
G - The number of herbivores.
H - The number of carnivores.
I - The number of top-predators.
J - F,G,H and I are shown in this graph.
The End.
