-- >>> let k1 = [6, -3, 0, 0, 0, 0, 0] :: [Double]
-- >>> let k2 = [-3, 10.5, -7.5, 0, 0, 0, 0] :: [Double]
-- >>> let k3 = [0, -7.5, 12.5, 0, 0, 0, 0] :: [Double]
-- >>> let k1 = [6, -3, 0, 0, 0, 0, 0] :: [Double]
-- >>> let k2 = [-3, 10.5, -7.5, 0, 0, 0, 0] :: [Double]
-- >>> let k3 = [0, -7.5, 12.5, 0, 0, 0, 0] :: [Double]