Hi everyone,

I want to write Weymouth equation in GAMS and solve it using MINLP solvers. here is the equation :

The problem is : I cant solve my model in GAMS due to “sign” operator. I received infeasible error when using “DICOPT” or “BARON” solver due to “sign” operator. Only the “SBB” solver starts to solving the model but it never ends.

I also try to define “sign” operator by myself but we cant use variables in “$” operator in GAMS to define it.

So, please help me to define Weymouth equation and solve my model in GAMS.