Re: minGW 'make check' errors

[PhilipNienhuis]

PhilipNienhuis wrote
> 
> Rik-4 wrote
>> 11/3/13
>> 
>> This bug report details some errors which apparently only appear on the
>> minGW system (https://savannah.gnu.org/bugs/?32036).
>> 
>> Specifically, it seems that log2 (Inf) = Inf on all other platforms and
>> NaN
>> on minGW.  Given that minGW is linking against Windows math libraries,
>> and
>> I don't see Microsoft changing anytime soon, I think we should make
>> exceptions for these two tests when minGW is detected.  After all,
>> reporting them as failures isn't going to change Octave's code (log2(Inf)
>> should be Inf), nor is it going to be a spur to Microsoft to change their
>> libraries.  Thus, the point of a failing test being a prod to get
>> something
>> fixed is rendered moot.
> Is that true, that it is Windows' low-level math libs that screw up? I'd
> expect that they are as tied to the HW (CPU/FPU) as e.g., Linux low-level
> math libs. I really see no reason for Microsoft to stick to returning
> inappropriate numeric exception values given the enormous proliferation of
> Windows in the engineering and scientific world. But I really don't know
> the exact details.
> 
> I'd rather expect that it is MinGW runtime math libs ("upstream") that get
> things wrong. An example of MinGW low-level code is here:
> https://www.gitorious.org/mingw/mingw-runtime/source/77108e3eb6c1896f3d1aa5ad7dcd2d8225280125:mingwex/math/powl.c
> My C/C++ skills surely are somewhat lacking but this code piece suggests
> me it cannot be ruled out yet that the key is in the MinGW math libs.
> FYI, Python seems to have wrappers for special values, see:
> http://bugs.python.org/review/11888/diff/2544/Modules/mathmodule.c?context=75&column_width=80
> Wrappers give me a taste of performance hits, but maybe they can be
> implemented cleverly.
> 
> Makes me wonder what Michael Goffioul's MSVC binaries make of it.

I just tried to run __run_test_suite__.m on Michael's MSVC 3.7.2+ snapshot
binary; unfortunately it crashed (and the whole window vanished) before it
reached data.cc ......

Philip



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