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Garden with Insight Kurtz-Fernhout Software
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Garden with Insight v1.0 Help: daily variable/state variable/parameter

This simulation has a daily time step, which means that calculations are carried out only once per simulated day. The word "today" is used in the simulation to show you that a value was calculated for the last day simulated. For example "Solar radiation today" means the total amount of solar radiation making its way to the garden during the last simulated day. Daily values change every day, as opposed to state variables and parameters. State variables simulate some physical things that persist from one day to the next, such as soil pH, and may or may not change every day (they simulate the state of something). Parameters never change at all. Parameters can change how the simulation behaves by changing the calculation of other variables, but they are never themselves changed.

As an example, you could think of your height as a state variable (it changes only slowly), what you eat today as a daily variable (it changes every day), and your genetic tendency toward a particular height as a parameter (it influences how tall you are, but you can't change it).

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Updated: March 10, 1999. Questions/comments on site to
Copyright © 1998, 1999 Paul D. Fernhout & Cynthia F. Kurtz.