[Libreoffice-bugs] [Bug 114051] New: tests sc_array_functions_test fail due to floating point precision

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=114051

            Bug ID: 114051
           Summary: tests sc_array_functions_test fail due to floating
                    point precision
           Product: LibreOffice
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Calc
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: miltonvandersloot at fake-box.com

The test ArrayFunctionsTest::testArrayFormulasFODS (files
sc/qa/unit/functions_test.cxx, sc/qa/unit/functions_array.cxx) fails the test
document sc/qa/unit/data/functions/array/fods/linest.fods. Opening the files in
sc/qa/unit/data/functions/array/fods/ reveals also that the file logest.fods
also fails (the others do not fail for me).

Error message in the compile run (Note that 1 = TRUE, 0 = FALSE in the
document)


functions_test.cxx:43:Assertion
Test name: ArrayFunctionsTest::testArrayFormulasFODS
double equality assertion failed
- Expected: 1
- Actual  : 0
- Delta   : 1e-14


The issue seems to be (again) floating point precision. Indeed, I've compiled
LibreOffice with FMA (fused multiply-add) instructions, if I disable them, i.e.
passing -ffp-contract=off to the compiler, then the tests succeed. Note that
FMA has slightly different floating point precision than ordinary plus and mult
[0, 1].

Mentionable commits:

* Add logest.fods test:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=588ebef9e8d1e2c703b79f51f2a1c8004cd7d96d
* Add linest.fods test:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=0523e11a2530ed101c580f93f94a4180e9dc0c9e
* Disable tests on 32-bit x86-linux due to floating point weirdness:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=b9a27d5856f60688456762bfcc29c38670009254

[0] https://en.wikipedia.org/wiki/Fused_multiply-add
[1] https://github.com/uclouvain/openjpeg/issues/1017

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