this post was submitted on 27 May 2024
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134
How Python Compares Floats and Ints: When Equals Isn’t Really Equal (blog.codingconfessions.com)
submitted 5 months ago by [email protected] to c/[email protected]
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[–] [email protected] 11 points 5 months ago (1 children)

Did nobody read the manual?

IEEE 754 double precision: The 53-bit significand precision gives from 15 to 17 significant decimal digits precision.

[–] [email protected] 2 points 5 months ago (1 children)

I'm not sure where the 17 comes from. It's 15.

[–] [email protected] 4 points 5 months ago

The "15 to 17" part is worded somewhat confusingly, but it's not wrong.

The number of bits contained in a double is equivalent to ~15.95 decimal digits. If you want to store exactly a decimal number with a fixed number of significant digits, floor(15.95) = 15 digits is the most you can hope for. However, if you want to store exactly a double by writing it out as a decimal number, you need 17 digits.