curvature versus slope
  n = 877989 
  X=0, Y = 32.56 +/- 16.31 
  Weighted least-squares fit:  Y = 67.8 + 1.635 X  + -0.01653 X**2 

slope versus dZ, curvature < 5
  n = 5457 

  Weighted least-squares fit:  Y = 25.8 + -0.023 X  + -0.00064 X**2 
     at X = 100, Y = 17.0 
     Bad fit. P2 = 0
slope versus dZ, curvature < 15
  n = 20427 

  Weighted least-squares fit:  Y = 21.0 + 0.150 X  + 0.00004 X**2 

curvature versus dZ, slope < 10
  n = 160 

  Weighted least-squares fit:  Y = 38.7 + -9.498 X  + 0.09960 X**2 


Number of samples 881808
Max dz = 900
Mean dz = 50
RMS dz = 68.2348884369
100cm = 87.3987307895 percentile value of dz