Parabolas, numerically

Recap, and background Two posts ago we showed how, given four points in the plane in general position, but with a few restrictions, it was possible to find two parabolas through those points. We used computer algebra. The steps were: Create four equations \[ (Ax_i+By_i)^2+Cx_i+Dy_i+E=0 \] for each of the four \((x_i,y_i)\) coordinates. Solve the first three equations for \(C\), \(D\) and \(E\):…