Why the output is different from the expected answer

Question

The expected answer is 0.0 but it shows something different
https://code.sololearn.com/cGE9URcrKA3K/?ref=app

Answer 1

Follow this link:

https://stackoverflow.com/q/588004/9166287

Answer 2

https://www.sololearn.com/Discuss/1477626/?ref=app

Answer 3

That's what i call an error

Answer 4

Hi