function china_normal ( )

  data = load ( 'china_data.txt' );
  year = data(:,1);
  income = data(:,2);
  n = length ( year );

  A = zeros ( n, 2 );
  A(:,1) = 1.0;
  A(:,2) = year;

  AtA = A' * A;
  Aty = A' * income;

  bm = AtA \ Aty;

  fprintf ( 'Best formula is income = %g + %g *year\n', bm(1), bm(2) );

  return
end

