I have a large optimization problem with linear, and non linear constraints, and bounds. The solver I have been using is fmincon. I need to carry out different optimizations with all the design variables, and only a portion of the design variables. To this goal, I have chosen to impose equal lower and upper bound for the variable that should not part of the problem. I know that is not an elegant approach but the code modifications are limited. Is there any other approach you would reccomend with limited impact on the code?