Hi, this is my first question on Gams Forum.

I’m now modelling with gams, and having a trouble.

I have a variable name as A.

A(machine, time) only has value of -1, 0, 1 as its value.

Actually, 1 means ‘turning on a machine’, -1 means ‘turning off machine’ in my model.

I would like to extract only ‘1’ and ‘-1’ value from A.

I tried introducing new variables such as A_positive and A_negative.

Adding two more equations in my model.

A_positive(machine, time) = max(A(machine, time), 0);

A_negative(machine, time) = min(A(machine, time), 0);

But, it does not work with error message below.

“**Endogenous function argument(s) not allowed in linear models**”

Is there any other way that I can do this?

Thanks in advance.