Float sum broken?

Question

print(0.1 + 0.2 == 0.3)

returns

False

Why?

score 4 · Accepted Answer · edited May 23 '17 at 10:29

4

It's not broken, that's how floating point arithmetic works.

Is floating point math broken?

I recommend reading this http://blog.reverberate.org/2014/09/what-every-computer-programmer-should.html

edited May 23 '17 at 10:29

Community

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1

answered Sep 22 '14 at 08:43

Khalil

825
1
6
7

score -1 · Answer 2 · answered Sep 22 '14 at 08:45

-1

It's a floating point precision issue. Basically floats cannot all be represented accurately in binary (and thus the underlying functions are working with imprecise representations of the numbers that you intend to use). Try using decimal.Decimal.

from decimal import Decimal
print Decimal('0.1') + Decimal('0.2')

answered Sep 22 '14 at 08:45

BWStearns

2,567
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This does not work either. – Realistic Feb 08 '17 at 07:46
SO won't let me remove my downvote :(. The most important part of this answer is to pass `Decimal` STRINGS not floats. – Realistic Mar 09 '17 at 22:46

Float sum broken?

2 Answers2

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