If you use several algebraic Additional Variables (AVs), it is not obvious, in which order they are processed. Consider the following example: You defined two algebraic AVs AV1 and AV2, where AV2 depends on AV1. You will then notice, that when AV1 changes, the value of AV2 changes one coefficient loop or one iteration later, that is it lags one coefficient loop/iteration behind. The process order of algebraic AVs is reversed alphabetical. That means, AV2 will be updated before AV1 is updated and thus uses the old value of AV1. This is what causes the lag/update shift in the current example. To avoid it, you should switch the dependency and make AV1 depending on AV2. Then the dependent variable AV1 will be updated after the independent variable AV2 and no update shift occurs. Key Words: Algebraic Additional Variable, process order, calculation order, update order