What is wrong with subtraction? Calculation mistake

[Domkrat 1]

Edited September 12, 2013 by Domkrat

[gammadust 12]

It is not the operations that differ, it is the irrational numbers that suffer limitations (errors) in its binary representation. Prety much the same way you can't represent certain fractions absolutely in our familiar decimal system (ie. 1/3 = 0.33333... ad infinitum).

it looks that way because the input terms you're comparing in the operations yield or not such a representation error.

8 - 7.999 vs 0.01 + 7.99

the issue with its representation might turn up either on the input of the operation or on it's ouput, that's why it appears inconsistent (ie. conversion from decimal to binary or vice versa)

more here

Edited September 12, 2013 by gammadust