Calculating Logarithms with Python

问题

I am trying to calculate logarithms using the math module of python (math.log(x,[base]), however when I use float(raw_input) for the x and base values, it gives me the error, ZeroDivisionError: float division by zero.

x = 9.0
base = 3.0

回答1:

Nonsense, it works perfectly well

>>> import math
>>> x=float(raw_input())
9.0
>>> base=float(raw_input())
3.0
>>> math.log(x, base)
2.0

Why don't you show us exactly how you reproduce the problem? wim is quite correct - a base of 1 will give that error

>>> base=float(raw_input())
1.0
>>> math.log(x, base)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: float division by zero

On the otherhand - if x<=0 you get a "math domain error"

>>> x=float(raw_input())
0
>>> math.log(x, base)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: math domain error

回答2:

You should avoid x<=0 as it is not defined !

来源：https://stackoverflow.com/questions/9883317/calculating-logarithms-with-python