To reproduce this bug: In a new spreadsheet, start the numbers in a column as follows: 1.0, 1.1, 1.2, 1.3 and then select all of them and drag so as to autofill the rows after the last number. As expected, Calc autofills them as 1.4, 1.5, 1.6, 1.7, etc. Now, try the exact same thing but starting with a number other than 1. Say, 3.0, 3.1, 3.2, 3.3, etc. Calc does not autofill the column as 3.4, 3.5, 3.6, etc. Instead, it fills as 4.0, 4.1, 4.2, 4.3, 5.0, 5.1, 5.2, 5.3, 6.0, etc.
[Reproducible] with "LibreOffice 3.4.0RC1 – WIN7 Home Premium (64bit) German UI [OOO340m1 (Build:11)]" Seems to be a very old bug, I also see it in OOo 1.1.4, 3.1.1, 3.4dev I also see some curious side effects, pls. see attached spreadsheet. Numbers until row 10 are source, starting with 11 is result of auto fill using fill handle with all cells containing numbers marked when starting auto fill. Blue numbers have been created by manual input (color added after autofill), black numbers in rows with row number smaller than 11 have been created by a calculation. Column A is expected behavior Column B shows wrong behavior due to report Column D: I typed 3.1, 3.2 into D7:D8, then I used autofill handle to fill D9:D10. Now D7:D10 looks as B7:B10, but result is completely different, here autofill works as expected with autofill D7:D10 using handle to fill to D11:D14 @Kohei: Please feel free to reassign if it's not your area!
Created attachment 46969 [details] Sample Document, see Comment 1
Solved it by allowing the autofill increment calculation to have a bit more tolerance when checking that the increment between each cells is the same. This has been a pure floating point problem.
Markus Mohrhard committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=cc94996d96ea8d8e3d136af66846707f9b838bbf autofill increment needs a bit more tolerance, fdo#37424
Xisco Fauli committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/2fce798d70bb39fe1b1dc95e2661e5836026de1a tdf#37424: sc_ucalc: Add unittest It will be available in 7.2.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.