curvature versus slope
  n = 1382510 
  X=0, Y = 40.11 +/- 23.78 
  Weighted least-squares fit:  Y = 67.3 + 1.480 X  + -0.01464 X**2 

slope versus dZ, curvature < 5
  n = 27073 

  Weighted least-squares fit:  Y = 46.6 + 0.234 X  + -0.00249 X**2 
     at X = 100, Y = 45.1 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 67657 

  Weighted least-squares fit:  Y = 50.3 + 0.061 X  + 0.00094 X**2 

curvature versus dZ, slope < 10
  n = 6295 
  X=0, Y = 50.06 +/- 38.41 
  Weighted least-squares fit:  Y = 52.6 + 1.610 X  + -0.38155 X**2 


Number of samples 1406036
Max dz = 900
Mean dz = 71
RMS dz = 93.7976545549
100cm = 74.5217049919 percentile value of dz