Dear all, I read some advices about the Hall effect (4-leads measurement) in previous posts referring to the code on the website: http://nbviewer.ipython.org/github/topocm/topocm_content/blob /master/w3_pump_QHE/Laughlinargument.ipynb However, I'm wondering if the following code is well correct in order to get the potential of each lead when a current I=1 is "imposed" between the contacts 4 and 5. r = np.linalg.inv(G) V = r.dot(np.array([0, 0, 0, 1, -1])) where G is the conductance matrix ( G[i,j] gives the conductance between lead i and j) and hence, r is the resistance matrix. V[0] is the potential of the lead 0 V[1] is the potential of the lead 1 V[2] is the potential of the lead 3 This would mean that, for example, V[0] = r[3,0] - r[4,0] However, is it more correct to write V[0] = r[3,0] - r[0,4] ? Indeed, r[0,4] is not equal to r[4,0] when we apply a magnetic field (the time reversal symmetry is broken). I think it is better to use r[0,4] in order to set a current flowing from lead 4 to lead 5. Am I right? Thank you in advance for your help. Best regards, D. Cabosart