*********************************
 Linear fit:
 solution =
     0.106
     0.915
 cov =
     0.603    -0.085
    -0.085     0.017
 *********************************
 Fit with parabola:
 solution =
     0.461
     0.687
     0.022
 cov =
     1.166    -0.446     0.035
    -0.446     0.248    -0.023
     0.035    -0.023     0.002