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 2 years ago
x = 10.0
for i in range(10):
x +=0.1
print x == 11.0
Why is this false? I print x and it equals 11.0
 2 years ago
x = 10.0 for i in range(10): x +=0.1 print x == 11.0 Why is this false? I print x and it equals 11.0

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rsmith6559
 2 years ago
Best ResponseYou've already chosen the best response.1Floating point is basically a binary scientific notation. It's accuracy is greatest when dealing with numbers that are close to a power of 2. A number like 11.0, although it prints as 11.0, is probably several ten thousandths off. That's enough so that it doesn't compare equal to your literal 11.0.

hootenanny
 2 years ago
Best ResponseYou've already chosen the best response.0At the point in the lecture series where I'm at, the prof alludes to a future lecture that discusses the internal representation of reals ie floating point. I'm guessing that if there's a function that can specify that the real number be accurate to the nearest tenth then I imagine this code snippet could work.

hootenanny
 2 years ago
Best ResponseYou've already chosen the best response.0I found this technical explanation http://docs.python.org/2/tutorial/floatingpoint.html#tutfpissues

silversteed
 2 years ago
Best ResponseYou've already chosen the best response.0Thank you for the answer. I thought that was the reason for this output. Didn't expect it on a practice quiz.
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