A method of solving a control problem in a processing plant is provided by modification of at least two manipulated variables within the manipulation range thereof, wherein the manipulated variables are associated with one or more processing unit(s), and the at least two manipulated variables affect at least one process variable of the processing plant. The method includes the following steps: establishing a value distribution of the at least one process variable for different value combinations of the at least two manipulated variables within the manipulation range thereof, taking into account one or more process parameter(s), and determining a control curve on the basis of the value distribution of the process variable for modifying the at least two manipulated variables in order to switch the processing plant from the start state to the end state, taking into account at least one boundary condition.