Python二次公式计算不准确

Question

这是我运行程序的主文件：

import math
import Disc

def main():

    coeffA = int(input('Enter the coefficient A: '))
    coeffB = int(input('Enter the coefficient B: '))
    coeffC = int(input('Enter the coefficient C: '))

    disc = Disc.discriminant(coeffA, coeffB, coeffC)

    while coeffA != 0:


        if disc > 0:

            solutionOne = (-coeffB + math.sqrt(disc)) / (2 * coeffA)
            solutionTwo = (-coeffB - math.sqrt(disc)) / (2 * coeffA)

            print('Solutions are: ' + str(solutionOne) + ' and ' + str(solutionTwo))

            coeffA = int(input('Enter the coefficient A: '))
            coeffB = int(input('Enter the coefficient B: '))
            coeffC = int(input('Enter the coefficient C: '))

        elif disc == 0:

            solutionOne = -coeffB / (2 * coeffA)

            print('Solution is: ' + str(solutionOne))

            coeffA = int(input('Enter the coefficient A: '))
            coeffB = int(input('Enter the coefficient B: '))
            coeffC = int(input('Enter the coefficient C: '))

        elif disc < 0:

            print('Equation has two complex roots.')

            coeffA = int(input('Enter the coefficient A: '))
            coeffB = int(input('Enter the coefficient B: '))
            coeffC = int(input('Enter the coefficient C: '))

    else:
        print('Program ended.')


# End of the main function

main()

这是你的名字光盘.py计算判别值以在main（）函数中使用的文件：

def discriminant(coeffA, coeffB, coeffC):

    value = (coeffB ** 2) - (4 * coeffA * coeffC)

    return value

这是运行程序时的输出：

Enter the coefficient A: 1
Enter the coefficient B: 2
Enter the coefficient C: -8
Solutions are: 2.0 and -4.0
Enter the coefficient A: 1
Enter the coefficient B: -12
Enter the coefficient C: 36
Solutions are: 9.0 and 3.0
Enter the coefficient A: 2
Enter the coefficient B: 9
Enter the coefficient C: -5
Solutions are: -0.75 and -3.75
Enter the coefficient A: 4
Enter the coefficient B: 6
Enter the coefficient C: 20
Solutions are: 0.0 and -1.5
Enter the coefficient A: 0
Enter the coefficient B: 0
Enter the coefficient C: 0
Program ended.

我期待以下根与上述输入：

Run1: 2, -4

Run2: 6

Run3: .5, -5

Run4: 'Equation has two complex roots.'

当我运行程序时，程序运行的最后3次的输出都是错误的，并且似乎将鉴别器设置为大于0的值，当我期望它根据计算的鉴别器更改输出时。提前谢谢！你知道吗

Answer 1

你好像少了一对括号。 这将修复错误：

if disc > 0:

            solutionOne = (-coeffB + math.sqrt(disc)) / (2 * coeffA)
            solutionTwo = (-coeffB - math.sqrt(disc)) / (2 * coeffA)

            print('Solutions are: ' + str(solutionOne) + ' and ' + str(solutionTwo))

            coeffA = int(input('Enter the coefficient A: '))
            coeffB = int(input('Enter the coefficient B: '))
            coeffC = int(input('Enter the coefficient C: '))

Answer 2

找到了解决办法。我的判别函数在while语句之外，因此当从用户输入3个变量时，它会在每个循环中保持计算出的第一个判别函数，这就是为什么每次运行都会产生2个答案的原因。通过将判别函数的位置更改为while语句内部，它现在将重新计算while语句的每个循环的判别函数。这是解决此问题的正确代码：

import math
import Disc

def main():



    coeffA = int(input('Enter the coefficient A: '))

    while coeffA != 0:

        coeffB = int(input('Enter the coefficient B: '))
        coeffC = int(input('Enter the coefficient C: '))

        disc = Disc.discriminant(coeffA, coeffB, coeffC)

        if disc > 0:

            solutionOne = (-coeffB + math.sqrt(disc)) / (2 * coeffA)
            solutionTwo = (-coeffB - math.sqrt(disc)) / (2 * coeffA)

            print('Solutions are: ' + str(solutionOne) + ' and ' + str(solutionTwo))

            coeffA = int(input('Enter the coefficient A: '))

        elif disc == 0:

            solutionOne = -coeffB / (2 * coeffA)

            print('Solution is: ' + str(solutionOne))

            coeffA = int(input('Enter the coefficient A: '))

        elif disc < 0:

            print('Equation has two complex roots.')

            coeffA = int(input('Enter the coefficient A: '))

    print('Program ended.')


    # End of the main function

产生的正确输出代码如下：

Enter the coefficient A: 1
Enter the coefficient B: 2
Enter the coefficient C: -8
Solutions are: 2.0 and -4.0
Enter the coefficient A: 1
Enter the coefficient B: -12
Enter the coefficient C: 36
Solution is: 6.0
Enter the coefficient A: 2
Enter the coefficient B: 9
Enter the coefficient C: -5
Solutions are: 0.5 and -5.0
Enter the coefficient A: 4
Enter the coefficient B: 6
Enter the coefficient C: 20
Equation has two complex roots.
Enter the coefficient A: 0
Program ended.

感谢Stack Overflow社区提供的所有帮助和建议！你知道吗