quadratic.py

import cmath
from typing import Tuple

def quadratic(a: float, b: float, c: float) -> Tuple[complex, complex]:
    ''' Compute the roots of the quadratic equation:

            ax^2 + bx + c = 0

        Written in Python as:

            a*x**2 + b*x + c == 0.0

        For example:

            >>> x1, x2 = quadratic(a=8, b=22, c=15)
            >>> x1
            (-1.25+0j)
            >>> x2
            (-1.5+0j)
            >>> 8*x1**2 + 22*x1 + 15
            0j
            >>> 8*x2**2 + 22*x2 + 15
            0j

    '''
    discriminant = cmath.sqrt(b**2.0 - 4.0*a*c)
    x1 = (-b + discriminant) / (2.0 * a)
    x2 = (-b - discriminant) / (2.0 * a)
    return x1, x2

if __name__ == '__main__':

    import doctest

    print(doctest.testmod())