A control system for determining a relation between stimulation settings for a brain stimulation probe and a corresponding V-field, the brain stimulation probe comprising multiple stimulation electrodes, the V-field being a potential distribution in brain tissue surrounding the stimulation electrodes, the control system comprising: - a pulse generator for applying a test current to the stimulation electrodes, - an impedance recording means or voltmeter for measuring an excitation voltage resulting from the applied test currents, - a memory, and - a processor being coupled with the memory for storing patient data for a computer program product for controlling the control system, which computer program product is operative to cause the processor to perform: - instructing the pulse generator for applying test currents to sequentially apply a test current to n stimulation electrodes, n being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, - instructing the impedance recording means or voltmeter for measuring an excitation voltage to measure at m stimulation electrodes an excitation voltage caused by each test current, m being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, from the stimulation settings and the measured excitation voltages, deriving an (m * n) coupling matrix, an element Zq,p in the coupling matrix reflecting an amount of electrical impedance between two of the stimulation electrodes, and - using the coupling matrix for determining the relation between the stimulation settings and the corresponding V-field, wherein the processor is further arranged for - receiving a predetermined set of stimulation settings, - using the relation between the stimulation settings and the corresponding V- field for determining the V-field corresponding to the predetermined set of stimulation settings and - using the relation between the stimulation settings and the corresponding V- field for determining a set of required stimulation settings for obtaining the target V-field - a pulse generator for applying a test current to the stimulation electrodes, - an impedance recording means or voltmeter for measuring an excitation voltage resulting from the applied test currents, - a memory, and - a processor being coupled with the memory for storing patient data for a computer program product for controlling the control system, which computer program product is operative to cause the processor to perform: - instructing the pulse generator for applying test currents to sequentially apply a test current to n stimulation electrodes, n being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, - instructing the impedance recording means or voltmeter for measuring an excitation voltage to measure at m stimulation electrodes an excitation voltage caused by each test current, m being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, from the stimulation settings and the measured excitation voltages, deriving an (m * n) coupling matrix, an element Zq,p in the coupling matrix reflecting an amount of electrical impedance between two of the stimulation electrodes, and - using the coupling matrix for determining the relation between the stimulation settings and the corresponding V-field, wherein the processor is further arranged for - receiving a predetermined set of stimulation settings, - using the relation between the stimulation settings and the corresponding V- field for determining the V-field corresponding to the predetermined set of stimulation settings and - using the relation between the stimulation settings and the corresponding V- field for determining a set of required stimulation settings for obtaining the target V-field - instructing the pulse generator for applying test currents to sequentially apply a test current to n stimulation electrodes, n being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, - instructing the impedance recording means or voltmeter for measuring an excitation voltage to measure at m stimulation electrodes an excitation voltage caused by each test current, m being a number between 2 and the number of stimulation electrodes of the brain stimulation probe, from the stimulation settings and the measured excitation voltages, deriving an (m * n) coupling matrix, an element Zq,p in the coupling matrix reflecting an amount of electrical impedance between two of the stimulation electrodes, and - using the coupling matrix for determining the relation between the stimulation settings and the corresponding V-field, wherein the processor is further arranged for - receiving a predetermined set of stimulation settings, - using the relation between the stimulation settings and the corresponding V- field for determining the V-field corresponding to the predetermined set of stimulation settings and - using the relation between the stimulation settings and the corresponding V- field for determining a set of required stimulation settings for obtaining the target V-field