FREE

From ASCEND

The FREE keyword is used in the METHODS section of your model when you want to un-fix a variable, such that ASCEND's solver will attempt to find its value by solving for it.

Often the FREE statement is not required, because by default all variables in a model are FREE when the model is created. You might sometimes want to write METHODS that re-configure your model in certain ways. Following the example from the FIX page, you might, for example, create the following additional METHOD:

(* add this to the example on the FIX page *)
METHOD solve_x;
    (* reconfigure the model to solve for x such that y=0 *)
    FREE x;
    FIX y;
    y:= 0;
END solve_x;