why 1-0.4 = 0.6 vs 1 - 1.4 = -0.399999999999 and 0.1 - 0.5 = -0.4 vs 0.2 - 0.6 = -0.3999999 How to make the calculation consistent? What the best way to deal with that to be able to compare (0.2 - 0.6) == (0.1 - 0.5) to get true, not false as it is right now Julia ver 1.11.5

Floating Point Math Also PSA: floating-point arithmetic

Mose’s answer is what you need to read, but also just to directly answer your question [image] BMval: What the best way to deal with that to be able to compare (0.2 - 0.6) == (0.1 - 0.5) to get true, not false as it is right now julia> (0.2 - 0.6) ≈ (0.1 - 0.5) true (that’s \approx<TAB>)

Oh, that question wasn’t there when I replied :sweat_smile:

To build on previous answers: checking for precise equality in floating point math should be used in only specific situations and with an understanding of roundoff as you see it here. The issue is that the decimal system used by humans is not perfectly matchable by the base-2 floating point system m…

Why 1-0.4 = 0.6 vs 1 - 1.4 = -0.399999999999

General Usage

giordano May 19, 2025, 2:37pm 2

Also PSA: floating-point arithmetic

Topic		Replies	Views
Float representation of the same number may not be equal? General Usage question	10	1030	November 19, 2019
PSA: floating-point arithmetic Offtopic	13	7878	July 8, 2021
Approx with a weird behaviour General Usage	1	412	January 16, 2019
Float comparison error General Usage	4	1312	June 19, 2018
Why do simple arithmetics cause weird Precision bugs General Usage	10	451	September 10, 2024

Why 1-0.4 = 0.6 vs 1 - 1.4 = -0.399999999999

Related topics