tests sc_array_functions_test fail due to floating point precision

[Stephan Bergmann]

On 12/02/2017 08:47 AM, Milton Vandersloot wrote:
> 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 GCC, then the tests succeed. Note that FMA has slightly different floating point precision than ordinary plus and mult [0, 1].

What is ultimately missing, I think, is a spec what the acceptable 
results of calculations in Calc are, and tests written so that they 
check whether or not the calculated results are in the acceptable ranges.