ford_model:
  Data from ford_data.txt involves n = 23 items with dimension d = 3

  Data statistics:
    Min      =  [1993. 5000. 5500.]
    Max      =  [ 1998. 72000. 11000.]
    Range    =  [5.0e+00 6.7e+04 5.5e+03]
    Mean     =  [ 1996.73913043 35000.          9332.26086957]
    Variance =  [1.41020794e+00 3.22608696e+08 2.21848671e+06]
  Graphics saved as "ford_mileage_price.png"
  Graphics saved as "ford_year_price.png"
Traceback (most recent call last):
  File "ford_model.py", line 132, in <module>
    ford_model ( )
  File "ford_model.py", line 80, in ford_model
    print ( '  c1=', c )
NameError: name 'c' is not defined