Description: calc doe's some 'tie to zero' rounding, acc. @erAck intended for integer values but imho affecting all calculations, this rounding sometimes has evil effects, e.g. '=(2^53+31-2^53)+(2^53-31-2^53)+(2^53+31-2^53)+(2^53-31-2^53)' should mathematical result in '0' (the subterms in brackets cancel each other out), 'fp-math' calculates '2' because above 2^53 IEEE 754 is limited to the 'even integers' and some small rounding steps in, calc calculates '64' reg. unneccessary rough rounding and either different effect of it below and above a magnitude range border (2^53), or different effect for '+' vs. '-', Steps to Reproduce: 1. calculate '=(2^53+31-2^53)+(2^53-31-2^53)+(2^53+31-2^53)+(2^53-31-2^53)' 2. 3. Actual Results: 64 Expected Results: '0' or maximal tolerable '2', Reproducible: Always User Profile Reset: No Additional Info: Version: 7.1.0.0.alpha1+ (x64) Build ID: b61bf7c7cfcf97a5ade6d130873af146670bc2ee CPU threads: 8; OS: Windows 6.1 Service Pack 1 Build 7601; UI render: default; VCL: win Locale: de-DE (de_DE); UI: en-US Calc:
(In reply to b. from comment #0) > calc doe's some 'tie to zero' rounding, acc. @erAck intended for integer > values but imho affecting all calculations, I never said the tie to zero was intended for integer values. Otherwise agree, that should be reworked.
hello @erAck, sorry, maybe i (or you?) was lost in the nested 'non' and 'not's of: 'Anyway, you hit an effect of the approxAdd() function used to normally eliminate accuracy limitations when adding/subtracting not non-ambiguous representable integer values with opposite signs of similar magnitudes by scaling to 2^-48 and thus rounding off the least significant 4 bits to yield a result of 0.0, i.e. to let 0.3-0.2-0.1==0.0.', cited acc. https://ask.libreoffice.org/en/question/274247/calc-wrong-calculation-would-like-a-recheck/,
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