`single_positive_root_of_cubic_equation(0, 1, 0, - 9),` fails with `mathlib.C:196: assertion 'y3 >= 0' failed in single_positive_root_of_cubic_equation`
single_positive_root_of_cubic_equation(0, 1, 0, - 9),fails with
mathlib.C:196: assertion 'y3 >= 0' failed in single_positive_root_of_cubic_equation