code: function H(x) {
  
    var z = new Fraction(1).sub(new Fraction(4).mul(x[0]));
  
    return [
    new Fraction(-2).div(z),
    new Fraction(1).div(z),
    new Fraction(1).div(z),
    new Fraction(-2).mul(x[0]).div(z),
    ];
  }
docs: /*
  We have the polynom f(x) = 1/3x_1^2 + x_2^2 + x_1 * x_2 + 3
  
  The gradient of f(x):
  
  grad(x) = | x_1^2+x_2 |
  | 2x_2+x_1  |
  
  And thus the Hesse-Matrix H:
  | 2x_1  1 |
  |  1    2 |
  
  The inverse Hesse-Matrix H^-1 is
  | -2 / (1-4x_1)    1 / (1 - 4x_1)     |
  | 1 / (1 - 4x_1)   -2x_1 / (1 - 4x_1) |
  
  We now want to find lim ->oo x[n], with the starting element of (3 2)^T
  
   Get the Hesse Matrix