1. A process for producing flat and annular-cross-section extrudates by means of an extrusion system, the extrusion system having an extrusion nozzle in the form of a wide slit or ring nozzle, and having a plurality of local adjustment zones located offset from a draw-off direction in which actuators are triggered for attaining an extrudate command thickness profile, and wherein the extrudate thickness is detected at positions located offset from the draw-off direction by means of a thickness gauge, said process comprising optimization of an extrudate thickness distribution carried out by minimizing the extrudate thickness deviation from a command thickness profile which is specified transversely to the draw-off direction by means of an evolution strategy method, in which in each case as a consequence of random changes (mutations) in control variables used in the context of a specifiable distribution density function (standard deviation), new control variables for final control elements included in said extrusion system, which affect the thickness distribution, are ascertained in the local control zones, [and]using a preselectable suppression rule (selection) in which a selection of control variables that are improved in view of a specified extrudate command thickness profile is made, triggering the final control elements in local control zones of the extrusion system, in order to carry out a following evolution step, and wherein the evolution strategy method is adapted to various production conditions or for increasing the convergence, in order to attain an optimized setting of the final control elements in a short time, said evolution strategy method using: prior process knowledge in the form of a transfer function that reproduces a given dependency of output variables on the control variables, or automatic adaptive process knowledge about the transfer function between local influence on thickness and actually measured values of the extrudate thickness distribution or both said prior process knowledge and said automatic adaptive process knowledge.