#encoding: utf-8

def f(x)
  0.6 * (x ** 2)
end

def nn(x, table, n)
  nn_val = 0
  for i in 0..n do
    div_diff = 0
    for j in 0..i do
      d = 1
      for k in 0..i do
        d *= (table[j][:x] - table[k][:x]) if j != k
      end
      div_diff += table[j][:y].to_f / d.to_f;
    end
    for k in 0..i do
      div_diff *= x - table[k][:x]
    end
    nn_val += div_diff
  end
  return nn_val
end

n = 6
table = []

for i in 0..n
    table[i] = {x: i/n.to_f, y: f(i/n.to_f)}
    puts table[i][:y]
end

puts nn(0.5, table, n)