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<p class="MsoNormal">Thanks again. I¡¯ve added a note to the issue, and raised a <a href="https://sourceforge.net/p/mingw-w64/bugs/916/">
bug</a> against mingw. (And also updated <a href="https://sourceforge.net/p/mingw-w64/bugs/515/">
another</a> related one.)</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is the right solution here to get it fixed in mingw? (And would that then be picked up in some future Haskell release?).</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I¡¯m also still a bit confused about ming-w64 and GCC (which are all very new to me). Per
<a href="https://en.wikipedia.org/wiki/Mingw-w64">Wikipedia</a> ¡°Mingw-w64 includes a port of the GNU Compiler Collection (GCC)¡±. So why does it have two different implementations of asinh? ¨C one for use by GCC (that gives good results), and one that is called
at runtime (that gives bad results)?.</p>
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<p class="MsoNormal">Thanks! David.</p>
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<p class="MsoNormal" style="border:none;padding:0cm"><b>From: </b><a href="mailto:minorinoki@gmail.com">arata, mizuki</a><br>
<b>Sent: </b>04 September 2021 12:41<br>
<b>To: </b><a href="mailto:dj112358@outlook.com">David James</a><br>
<b>Cc: </b><a href="mailto:haskell-cafe@haskell.org">haskell-cafe@haskell.org</a><br>
<b>Subject: </b>Re: [Haskell-cafe] Trouble with asinh (c calls with Doubles) in Windows</p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">FloatFnInverses is marked as ¡®expect_broken¡¯ on Windows:<o:p></o:p></p>
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<p class="MsoNormal"><a href="https://gitlab.haskell.org/ghc/ghc/-/blob/922c6bc8dd8d089cfe4b90ec2120cb48959ba2b5/testsuite/tests/numeric/should_run/all.T#L44-45">https://gitlab.haskell.org/ghc/ghc/-/blob/922c6bc8dd8d089cfe4b90ec2120cb48959ba2b5/testsuite/tests/numeric/should_run/all.T#L44-45</a><o:p></o:p></p>
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<p class="MsoNormal">And there¡¯s a relevant issue: <a href="https://gitlab.haskell.org/ghc/ghc/-/issues/15670">https://gitlab.haskell.org/ghc/ghc/-/issues/15670</a><o:p></o:p></p>
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<p class="MsoNormal">Mizuki<o:p></o:p></p>
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<p class="MsoNormal">2021/09/04 18:46<span style="font-family:"MS Gothic"">¡¢</span>David James <<a href="mailto:dj112358@outlook.com">dj112358@outlook.com</a>><span style="font-family:"MS Gothic"">¤Î¥á©`¥ë</span>:<o:p></o:p></p>
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<p class="MsoNormal">Hi - thank you for this. I was unaware of the ¡°constant folding¡± in GCC (and I¡¯m surprised it works for functions like asinh), but I can see that it explains the difference in behaviour.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">So I think this is a (possibly minor) bug that Haskell inherits from mingw-w64. I guess I should raise a GHC issue ¨C though I¡¯m not sure whether it would be best to try to fix within Haskell or within mingw-w64.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Also, I think the<span class="apple-converted-space"> </span><a href="https://gitlab.haskell.org/ghc/ghc/-/blob/master/testsuite/tests/numeric/should_run/FloatFnInverses.hs">FloatFnInverses.hs</a><span class="apple-converted-space"> </span>test
doesn¡¯t should be showing as a fail somewhere in the CI testing. (It doesn¡¯t give the expected output when I run it on Windows). Do you know whether/where I can see that? (I don¡¯t know what CI happens or how to view its output).<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Thanks again,<o:p></o:p></p>
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<p class="MsoNormal">David.<o:p></o:p></p>
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<p class="MsoNormal"><b>From:<span class="apple-converted-space"> </span></b><a href="mailto:minorinoki@gmail.com">arata, mizuki</a><br>
<b>Sent:<span class="apple-converted-space"> </span></b>03 September 2021 13:43<br>
<b>To:<span class="apple-converted-space"> </span></b><a href="mailto:dj112358@outlook.com">David James</a><br>
<b>Cc:<span class="apple-converted-space"> </span></b><a href="mailto:haskell-cafe@haskell.org">haskell-cafe@haskell.org</a><br>
<b>Subject:<span class="apple-converted-space"> </span></b>Re: [Haskell-cafe] Trouble with asinh (c calls with Doubles) in Windows<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi David,<br>
<br>
If I understand correctly, GHC uses mingw-w64¡¯s libc implementation on Windows.<br>
Since mingw-w64¡¯s math functions are not of very good quality, it is likely that asinh returns NaN for a very large input.<br>
<br>
As to why `asinh(1.7976931348623157e308)` in CAsinh.c produces (seemingly-correct) 710.4758, it is probably because the C compiler (GCC) uses a different implementation of asinh when doing constant folding.<br>
As a note, you may get a different (compile-time computed) result for `asinh(x)` if you set a more aggressive optimization flag.<br>
<br>
Mizuki</p>
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