https://bugs.documentfoundation.org/show_bug.cgi?id=162330
Mike Kaganski <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |NOTABUG --- Comment #3 from Mike Kaganski <[email protected]> --- This is not a bug; see FAQ: https://wiki.documentfoundation.org/Faq/Calc/Accuracy Specifically, you compare these calculations: 1. -22.67 2. 176 + 340 - 16.6 - 3.5 + (-60 - 50.02 - 8.55 - 4) 3. -244.1 + 221.43 First, let's look at #1. The number -22.67 is already not representable in Calc; an approximation is used, which is exactly > -22.6700000000000017053025658242404460906982421875 In #2, you perform the calculation in parentheses separately (just noting, because that affects the accuracy, because it excludes this part of calculation from Kahan summation algorithm). Its result is, exactly, > -518.5700000000000500222085975110530853271484375 Adding it to the rest of the sum, the result is, exactly, > -22.670000000000072759576141834259033203125 which differs from #1 by ~-7.1*10^-14. In #3, the result is, exactly, > -22.669999999999987494447850622236728668212890625 which differs from #1 by ~+1.4*10^-14. At the same time, it differs from #2 by ~+8.5*10^-14. Note that this last difference is the biggest. When you compare results of #1 and #2, or #1 and #3, they are considered equal, because their difference is smaller than a given relative threshold. But when you compare #2 and #3, the difference is larger than considered equal. Yes, the pure math isn't applicable to spreadsheets. Users must be prepared to that, and use relevant techniques (rounding, or approximate comparison). -- You are receiving this mail because: You are the assignee for the bug.
