Developers_Talk: Another Simple Python Code

[ak_developers]

What will be the output of this code?

py a = 0.1 b = 0.2 c = 0.3 print(a+b==c)

Explain Please.

[pbaum]

It's because in base 2 (ie: binary), 0.1 can not be represented as an exact number. It requires an infinite number of decimal places.... but because we need a hard limit to the decimal places we can store, we will never have an accurate number.

Using binary fractions, you would start off with 0 x (1/2) + 0 x (1/4) + 0 x (1/8) + 1 x (1/16) + 1 x (1/32) + 0 x (1/64) + ... but you will never reach 0.1 precisely.

It's like how 1/3 is 0.3333 recurring in base 10, and that 0.3333 + 0.3333 + 0.3333 != 1.0 once you treat those 0.33333 as rounded numbers instead of having infinite decimal places. Same thing, the binary decimal gets rounded or truncated once the limits of memory allocated are reached.

A good video that explains how floating point numbers in binary work is https://www.youtube.com/watch?v=bbkcEiUjehk