function JJ = Jacobiano2R(ang1,ang2,l1,l2)

 %-----------------------------------------------------------------
  JJ = [ -l1*sin(ang1)-l2*sin(ang1+ang2)   -l2*sin(ang1+ang2)
          l1*cos(ang1)+l2*cos(ang1+ang2)    l2*cos(ang1+ang2) ];
 %--------------------------------------------------------------end
