The Python Oracle

Why do Python's math.ceil() and math.floor() operations return floats instead of integers?

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Chapters
00:00 Why Do Python'S Math.Ceil() And Math.Floor() Operations Return Floats Instead Of Integers?
00:39 Answer 1 Score 117
00:58 Accepted Answer Score 107
01:31 Answer 3 Score 20
01:42 Answer 4 Score 18
02:33 Answer 5 Score 5
02:44 Thank you

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Full question
https://stackoverflow.com/questions/8582...

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Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...

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Tags
#python #math

#avk47



ANSWER 1

Score 117


As pointed out by other answers, in python they return floats probably because of historical reasons to prevent overflow problems. However, they return integers in python 3.

>>> import math
>>> type(math.floor(3.1))
<class 'int'>
>>> type(math.ceil(3.1))
<class 'int'>

You can find more information in PEP 3141.




ACCEPTED ANSWER

Score 107


The range of floating point numbers usually exceeds the range of integers. By returning a floating point value, the functions can return a sensible value for input values that lie outside the representable range of integers.

Consider: If floor() returned an integer, what should floor(1.0e30) return?

Now, while Python's integers are now arbitrary precision, it wasn't always this way. The standard library functions are thin wrappers around the equivalent C library functions.




ANSWER 3

Score 20


Because python's math library is a thin wrapper around the C math library which returns floats.




ANSWER 4

Score 5


Before Python 2.4, an integer couldn't hold the full range of truncated real numbers.

http://docs.python.org/whatsnew/2.4.html#pep-237-unifying-long-integers-and-integers