function [A,B] = calcul_AB( X,w )

global rs  Xls  Xm  Xlr  rr  J  P  Xrr  Xss  D

F_dr = X(5);        F_qr = X(4);

a71 = 3*P^2*Xm*F_dr / (8*J*w*D);

a72 = -3*P^2*Xm*F_qr / (8*J*w*D);

A = [  -rs*w*Xrr/D       -w         0        rs*w*Xm/D         0           0       0 
            w       -rs*w*Xrr/D     0            0         rs*w*Xm/D       0       0
            0             0      -rs*w/Xls       0             0           0       0
        rr*w*Xm/D         0         0       -rr*w*Xss/D       -w           0      F_dr
            0        rr*w*Xm/D      0            w        -rr*w*Xss/D      0     -F_qr
            0             0         0            0             0       -rr*w/Xlr   0
           a71           a72        0            0             0           0       0  ];
       
B = [ w 0 0 0
      0 w 0 0
      0 0 w 0
      0 0 0 0
      0 0 0 0
      0 0 0 0
      0 0 0 -P/(2*J)];       
       
return