The simulation process requires specification of control parameters for a simulation run. The specification control parameters are model variables that must be included in a model for it to simulate. These parameters are often Constants, though they need not be. The mandatory control parameters are:
TIME STEP = 0.5
| ~ | month |
| ~ | The integration solution interval. |
|
INITIAL TIME = 0
| ~ | month |
| ~ | The time at which the simulation begins. |
|
FINAL TIME = 80
| ~ | month |
| ~ | The time at which the simulation will end. |
|
SAVEPER = TIME STEP
| ~ | month |
| ~ | The frequency with which values are saved for later display |
|
The units of measure for the simulation control parameters define the units of Time, and should match. Simulation control parameters can be defined with any equation, though they are typically constants. It is also common, though not required, for SAVEPER and TIME STEP to be equal. When you start a new model Vensim will query you for the initial values of the simulation control parameters, but you can change them anytime. If you are using the Sketch tool you can change the simulation control parameters with the Model>Settings...>Time Bounds command.
