Quadratic equations solving using the Durand–Kerner method
x**4 + a * x**3 + b * x**2 + c * x + d = 0
The quadratic equation can be solved using a number of iterations according to the Durand–Kerner method.
The script accepts the values for coefficients a,b,c,d.
It then lists the roots with the residual. Roots can be complex numbers.
The script uses no imported libraries, it can also run in CPython on a PC.