The one accessible via: 'Tools -> Options... -> LibreOffice Calc -> Formula -> Detailed Calculation Settings' set to Custom, then 'Details...', then 'Test OpenCL' button. Because formulas are given like this: "=IF(ABS(C2-D2)<=3e-010,00,1)", the results are Err:509 all over the spreadsheet for me (Hungarian locale, decimal separator is comma). It doesn't really affect anything, hence the trivial severity, but it would be nice to have separators in functions changed to semicolon.
Aron, are you actually intentionally using that functionality, or did you just want to see what it does (or are you systematically going through all options etc)? As I say in my comment in https://gerrit.libreoffice.org/#/c/27450/2 , I am not sure whether that functionality even is of much use any more... The vague idea how it would be used has not really worked out. Would be better to remove unneeded code than to fix small issues in it.
(In reply to Tor Lillqvist from comment #1) I'm not using it, just found this among the Options when I was investigating bug 101049 (also did that out of curiosity). Indeed it doesn't seem to be much relevant, as it didn't show any issues when something was clearly wrong with a certain OpenCL-calculated formula, see the other bug report. I have no personal preference, and don't mind having this removed, proceed as you see fit.
Tor Lillqvist committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=d78012872a15cdd0347cbabfc13e03ce5511bf90 tdf#101063: Get rid of the whole "Test OpenCL" functionality while at it It will be available in 5.3.0. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Please backport to 5.2 and 5.1.
It is in 5.2 (1e0a8a26ce401aa84e065057d09b8a50dcdfc871, https://gerrit.libreoffice.org/27617 ). Not really worth it for 5.1.