python – 麻省理工学院开放课程,第3讲 – 数学问题

根据简单的数学计算,她使用的代码不应该是成功的.

## EXAMPLE: approximate cube root 
####################
#cube = 27
##cube = 8120601
##cube = 10000
#epsilon = 0.1
#guess = 0.0
#increment = 0.01
#num_guesses = 0
## look for close enough answer and make sure
## didn't accidentally skip the close enough bound
#while abs(guess**3 - cube) >= epsilon and guess <= cube:
#    guess += increment
#    num_guesses += 1
#print('num_guesses =',num_guesses)
#if abs(guess**3 - cube) >= epsilon:
#    print('Failed on cube root of',cube,"with these parameters.")
#else:
#    print(guess,'is close to the cube root of',cube)

这是她使用的代码,我遇到的问题是理解这部分：

while abs(guess**3 - cube) >= epsilon and guess <= cube:
#    guess += increment

如果guess是0.0,cube是27并且increment是0.01那么这个术语的数学应该是：

abs(0**3 - 27) = 27 #----- This is fine according to the code but the next step would be:#
abs(27.01**3 - 27) = 19677.878101

这应该阻止循环进一步工作.我的理解在某处显然是错误的,但我看不到哪里！

请停下来……