During active Constraint testing, Vensim forces the condition part of Constraint equations to be true, changing variable values or model structure where necessary.
| • | If the condition is an equality condition or Test Input, Vensim appends the equation to the existing model equation (remember that the equation may reference the original computed value for a variable). The new value for the variable is then used wherever the variable is used. |
| • | If the condition uses inequality, Vensim first tests to see if the inequality is true. |
| • | If it is true, the value of the variable is not changed. |
| • | If it is not true, Vensim makes it true by assigning the value just as if it were an equality condition. |
Having forced conditions to be true Vensim tests to see if the consequences are also true.
