logistic_errors:
  Use logistic_euler() to solve the logistic equation
  for an increasing number of steps N.
  Print the RMS error for each value of N.

   I     N   RMS

   1    10  0.0265782
   2    20  0.0126042
   3    40  0.00615806
   4    80  0.00304381
   5   160  0.00151308
   6   320  0.000754322
   7   640  0.000376605
   8  1280  0.000188164