Function robust_geo::sign_det_x_x2y2_plus_2x_det_x_y

pub fn sign_det_x_x2y2_plus_2x_det_x_y(
    a: Vector2<f64>, 
    b: Vector2<f64>, 
    c: Vector2<f64>, 
    u: f64, 
    i: Vector2<f64>, 
    j: Vector2<f64>, 
    k: Vector2<f64>
) -> f64

Computes the following sum of determinants.

│ a.x   a.x^2 + a.y^2   1 │     │ i.x   i.y   1 │
│ b.x   b.x^2 + b.y^2   1 │ + 2u│ j.x   j.y   1 │
│ c.x   c.x^2 + c.y^2   1 │     │ k.x   k.y   1 │

and returns a number with the same sign as the sum, or 0 if the sum is 0