bisection('sec2_1_2',-2,1.5,0.01)
  -2.000000000000000  -0.250000000000000  -1.125000000000000

  -1.125000000000000  -0.250000000000000  -0.687500000000000

  -1.125000000000000  -0.687500000000000  -0.906250000000000

  -1.125000000000000  -0.906250000000000  -1.015625000000000

  -1.015625000000000  -0.906250000000000  -0.960937500000000

  -1.015625000000000  -0.960937500000000  -0.988281250000000

  -1.015625000000000  -0.988281250000000  -1.001953125000000

  -1.001953125000000  -0.988281250000000  -0.995117187500000

diary off