A method for calculating a system by optimization, the method comprising the steps of: i. providing a set of system parameters so as to define a starting system, each system parameter being set up at a starting value; ii. defining a plurality of criteria; iii. associating for each criterion a cost function; iv. defining a plurality of global cost functions by associating to each global cost function at least one cost function; v. defining a vector of variable parameters associated to each global cost function by selecting for each vector of variable parameters at least one system parameter; vi. optimizing the plurality of global cost functions by modifying the values of the system parameters of the vectors of variable parameters so as to obtain an intermediate system; repeating step vi. until an equilibrium is reached so as to obtain a system.