exercise1.py:49: RuntimeWarning: invalid value encountered in subtract
  c6 = c6 - r * gradient_vector
exercise1:
  Data from playfair_data.txt involves n = 50 items with dimension d = 3
  Data statistics:
    Min      =  [1565.   26.    5.]
    Max      =  [1810.   99.   30.]
    Range    =  [245.  73.  25.]
    Mean     =  [1687.5      42.14     11.5816]
    Variance =  [5206.25        216.9704       52.74468944]
  C4 =  [ 5.45468037e+01 -2.95284893e-02]
  MSE4 =  1.4859182006507448
  R =  0.5   C6 =  [nan nan]   MSE6 =  nan
  R =  0.05   C6 =  [nan nan]   MSE6 =  nan
  R =  0.005   C6 =  [nan nan]   MSE6 =  nan
  R =  0.0005   C6 =  [nan nan]   MSE6 =  nan
  R =  5e-05   C6 =  [nan nan]   MSE6 =  nan
  R =  5e-05   C6 =  [nan nan]   MSE6 =  nan
  R =  5e-06   C6 =  [nan nan]   MSE6 =  nan
  R =  5e-11   C6 =  [ 4.71747801e+00 -7.16452600e-06]   MSE6 =  6.023356097786064