polynomial_function为二次多项式表达式，修改上述程序

如果`polynomial_function`表示的是二次多项式，我们可以简化`solve_polynomial_equation`函数，因为二次方程求根公式更为直接。假设`polynomial_function`总是返回一个包含系数(a, b, c)的列表，可以这样做：

def quadratic_expression_to_coefficients(expression):
    # 根据输入的二次多项式字符串解析出系数
    coefficients = expression.split(',')
    return [float(coeff) for coeff in coefficients]

def solve_quadratic_equation(quadratic_expression):
    a, b, c = quadratic_expression_to_coefficients(quadratic_expression)
    discriminant = b**2 - 4*a*c
    if discriminant > 0:
        x1 = (-b + discriminant**0.5) / (2*a)
        x2 = (-b - discriminant**0.5) / (2*a)
        return x1, x2
    elif discriminant == 0:
        x = -b / (2*a)
        return [x]
    else:  # complex roots
        real_part = -b / (2*a)
        imaginary_part = discriminant**0.5 / (2*a)
        return [real_part + imaginary_part * 1j, real_part - imaginary_part * 1j]

# 示例
expression = "1, -3, 2"  # 表示 ax^2 + bx + c 的形式
solution = solve_quadratic_equation(expression)