function mid2_2()
  format long
  x = [0.6 - cos(0.6), 0.7 - cos(0.7), 0.8 - cos(0.8), 0.9 - cos(0.9)];
  y = [0.6, 0.7, 0.8, 0.9];
  z = 0;
  sum = ones(1, 4);
  for i = 1:4
    for j = 1:4
        if (j ~= i)
          sum(i) = sum(i) * (z - x(j)) / (x(i) - x(j));
        end
    end
  end
  y*sum'
end