[Tutor] float.is_integer()

[Alan Gauld]

On 03/10/2020 13:53, Richard Damon wrote:
> On 10/3/20 5:51 AM, Alan Gauld via Tutor wrote:
>> On 03/10/2020 01:08, Zachary Ware wrote:
>>> Have a look at the repr of 23444444444444444.7777; a 64 bit floating point
>>> number cannot represent that number exactly.
>> So basically the float is just too big to include the fractional part.
>> Hmm, I wonder where the break off point is? Time to do some math...
>> Or play with the interpreter! :-)
>>
> Python floating point numbers have 52 significant bits + implied leading
> 1 + sign bit. Numbers less than 2^52 have fractional bits, 2^52 and
> bigger can not.


And just to prove it:

>>> 2**52
4503599627370496
>>> 4503599627370496.7.is_integer()
True
>>> 4503599627370495.7.is_integer()
False
>>>



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