10=>20, interp err = 0.0000e+00
20=>40, interp err = 0.0000e+00
40=>80, interp err = 0.0000e+00
80=>160, interp err = 0.0000e+00
160=>320, interp err = 0.0000e+00
320=>640, interp err = 0.0000e+00