Note that in all equations except the last, a subscript appears on left of the equals sign. For the Constants, the subscript task appears on the left, and three values (one for each task) appear on the right. For most Auxiliaries, the subscript task appears on both the right and the left. Things that are differentiated by task need to be caused by things that are differentiated by task.
An exception to this is the last equation. Here, task appears only on the right. The variable total work done is a single number representing the sum of all three task's work done. The subscript function SUM tells Vensim to add together all the values for the variable with the subscript that is marked by an exclamation point (!). Sometimes more than one subscript range appears in an equation, so the exclamation point is used to denote the subscript range being acted on (here by the SUM function).
| Ø | Select the menu Model>Check Model (Ctrl + T). |
You should get the message "Model is OK". If you don't, you will probably get a message "Incorrect number of subscripts for …(variable name)." The Equation Editor will open and position itself at the incorrect equation. Check that the equation exactly matches the equations above. If that equation matches, check the other equations. Modify, click OK, then do Model>Check Model again.
