Assigning Units to Variables

You manually assign units to stocks and converters in the model.

All stocks in a main chain are automatically assigned the same units that you assigned to any stock in the chain.

Units for flows are automatically assigned by the software based on the units you've assigned to their associated stocks. For example, if you assigned a unit of measure called "widgets" to a stock, and your model is running in months, any flows into or out of the stock would automatically be assigned the units "widgets per month", a built in unit definition with equation widgets/month.

Notes: If you add stocks or flows to the chain after you assign units, the new variables won't be automatically assigned units. To assign units to the new variables, assign units to any stock in the chain; everything else in the chain will automatically be assigned units.

If there's a unit-converted flow (one for which the Unit conversion check box is selected) in the chain, any flows or stocks beyond that flow will not be automatically assigned the same unit of measure; you have to manually assign units to those stocks yourself.

When you assign units to a variable, you can select from existing units, select from units already used in the model, create new units, or have the software suggest the appropriate units based on the variable's equation.

To Assign Units to a Variable

Use the following procedure to assign units to a variable by using the Units options on the Equation panel.

  1. Select the variable in the model diagram.
  2. Click the Equation tab of the Properties panel.
  3. Use the Units box at the bottom of the Equation panel to assign units to the variable:

  4. When the units you want to assign are displayed in the Units box, move on to your next task, or click to apply the units to the variable.

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