[ [ -1, 0, 0,  0, 1, 0, 0 ],
  [  2,-1, 0,  0, 0,-1, 0 ],
  [  0, 1,-1,  0, 0, 0, 0 ],
  [  0, 0, 1, -1, 0, 0,-1 ],
  [  0, 0, 0,3/5,-1, 0, 0 ],
  [  0, 1, 0,  0, 1, 0, 0 ],
  [  0,-1, 0,  0,-1, 0, 0 ],
  [  0, 0, 1,  0, 0, 0, 0 ] ]