Python数学响

Question

当我试图用Python计算一个非常大的数字时，我得到了一个错误。这是我的代码：

# Where fourthNumber = 2790
# and dee = 413
emm = math.pow(fourthNumber, dee)

我的错误是：

line 44, in <module>
    emm = math.pow(fourthNumber, dee)
OverflowError: math range error

有办法避免这个错误吗？我以为Python可以处理任意大的数字？还是我错了？如有任何帮助，我们将不胜感激。谢谢！

Answer 1

问题是math.pow(..)对浮点数起作用。在Python中，浮点数不是任意大的。只有ints是（在python-3.x中，而longs在python-2.x中）。

但是，如果这两个数字是整数，则可以使用**运算符，该运算符可以进行整数幂运算（当然，参数是整数）：

>>> 2790**413
10827693458027068918752254513689369927451498632867702850871449492721716762882046359646654407147290095143376244612860740505063304616869045757879636651922242895944635094287526023557872050108996014618928707382416906723717536207944990935946477343103732942220495426003253324856391048675505527041527544249845903325107575822015010197006079682477544271998209608154757421132764034059289159228295810448568286783859864141487725512980856505994152145510660350938086763233208252511256291934375881870590480237727775536326670654123168787472077359939510018827829233028430183558108518520524567765780717109616748933630364200317687291046055118737587697510939517252245710306646155772831436013971724481443654932630319085588147436112198934867224850036968074130558127066188475740553149587714112808551835880666012903651859580234129805580074844684526620091506655345299434455806896837926335229779632528684030400890708579038639280240022309690038032176604539091205540422068492362106868171343650410145963283813864374487990607671475570427243900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

但是，如果将其转换为float，则会得到：

>>> float(2790**413)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: int too large to convert to float

所以这个错误清楚地表明python不能像floats那样处理这个大数字

Answer 2

内置的pow使用整数运算：

>>> pow.__module__
'__builtin__'
>>> pow is math.pow
False
>>> pow(2790, 413)
108276934...

Answer 3

您可以处理任意大的整数数；math.pow浮点数操作。

2790**413>；1000**413=1e+1239，远远高于大约1e+308的浮点范围。

使用**停留在整数域内，并获取您的大整数。