A variable is specified by more than one assignment rule

Hi,

I have a species A_Total = a + b + c, where a, b and c are other species in the same compartment. I have to set a boundary condition that species 'a' is just equal to 'A_total - b - c' to implement the idea of my project.

I received the following message:

Invalid repeatedAssignment rule '[A_Total] = [a] + [b] + [c]'. The variable 'A_Total' is specified by more than one assignment rule.\n

Is there a way to handle this error and still implementing the idea?

Thank you

Answer 1

[Arthur Goldsipe]

It sounds like you have an ill-defined problem with an algebraic loop. Specifically, A_Total is a function of a, but a is a function of A_Total. To address this problem, you need to make a modeling decision about how these quantites should be determined, and then update the rules accordingly.

For example, yould could decide that A_Total should be set to a fixed value, and delete (or inactivate) the assignment rule that was setting A_Total.