python - FindRootTest 不工作

Question

File "/Users/SalamonCreamcheese/Documents/4.py", line 31, in <module>
    testFindRoot()
File "/Users/SalamonCreamcheese/Documents/4.py", line 29, in testFindRoot
    print " ", result**power, " ~= ", x
TypeError: unsupported operand type(s) for ** or pow(): 'tuple' and 'int'

任何帮助将不胜感激，我不明白为什么它说 result** power is of type(s)，我假设意思是字符串，为什么那是错误。提前感谢您的任何反馈。

def findRoot(x, power, epsilon):
    """Assumes x and epsilon int or float,power an int,
        epsilon > 0 and power >= 1
    Returns float y such that y**power is within epsilon of x
        If such a float does not exist, returns None"""
    if x < 0 and power % 2 == 0:
        return None
    low = min(-1.0, x)
    high = max(1,.0 ,x)
    ans = (high + low) / 2.0
    while abs(ans**power - x) > epsilon: 
        if ans**power < x:
            low = ans
        else:
            high = ans
        ans = (high +low) / 2.0
    return ans

def testFindRoot():
    for x in (0.25, -0.25, 2, -2, 8, -8):
        epsilon = 0.0001
        for power in range(1, 4):
            print 'Testing x = ' + str(x) +\
                  ' and power = ' + str(power)
            result = (x, power, epsilon)
            if result == None:
                print 'No result was found!'
            else:
                print " ", result**power, " ~= ", x

testFindRoot()

Answer 1

之后

result = (x, power, epsilon)

result 绑定(bind)到 3 元素元组。所以错误消息是完全准确的，您稍后会尝试将该元组提升到整数幂 power。 Python 没有为元组定义 __pow__，仅此而已。

大概您打算编码:

 result = findRoot(x, power, epsilon)

相反。