Sometimes Vensim will detect that more than one Equation has been defined for a variable that does not have any subscripts. This is normally the result of entering the same equation twice in the Text Editor. It is not possible to generate this condition using the Sketch Editor. To fix this you must go to the Text Editor and find the two equations for the variable. Using Entrain mode will help you find the first equation.
If you run into this problem in Vensim PLE, PLE Plus or Standard, it may be necessary to edit the model (.mdl) file in a separate text editor.
Multiple Definitions
Vensim will detect if more than one equation computes a value for a subscript element. Suppose, for example, you have the equations:
store: s1,s2 ~~|
profit[store] = revenue[store] - cost[store] ~ ~|
profit[s1] = revenue[s1] - cost[s1] - pothole tax ~ $/Year ~|
In this case there are two equations that compute a value for profit[s2]. Vensim will report this as an error. The first equation should use s1 instead of store as a subscript. You will need to look carefully at each equation for a variable and see which need to be corrected.
Used but Not Defined
It is permissible to only define a subset of the elements of a subscripted variable. Consider for example the equations:
plant : p1,p2,p3 ~~|
pp : p1,p2 ~~|
morale[pp] = normal moral * effect of fatigue[pp] ~ Haps~|
In this set of equations morale for p3 is simply not defined. If morale is only used with the Subscripts p1, p2 or pp this will not cause a problem. Suppose however you have the equation:
quality[plant] = norm quality[plant] * morale funct(morale[plant]/ normal morale) ~ Dmnl ~|
This equation uses morale[p3] and Vensim will report the error message:
ERROR: Used, not Computed "morale[p3]".
Selecting this error will position you on the first equation where the variable was used. In this case the equation defining morale needs to be generalized.
