Thanks again. I��ve added a note to the issue, and raised a bughttps://sourceforge.net/p/mingw-w64/bugs/916/ against mingw. (And also updated anotherhttps://sourceforge.net/p/mingw-w64/bugs/515/ related one.)
Is the right solution here to get it fixed in mingw? (And would that then be picked up in some future Haskell release?).
I��m also still a bit confused about ming-w64 and GCC (which are all very new to me). Per Wikipediahttps://en.wikipedia.org/wiki/Mingw-w64 ��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)?.
Thanks! David.
From: arata, mizukimailto:minorinoki@gmail.com
Sent: 04 September 2021 12:41
To: David Jamesmailto:dj112358@outlook.com
Cc: haskell-cafe@haskell.orgmailto:haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Trouble with asinh (c calls with Doubles) in Windows
FloatFnInverses is marked as ��expect_broken�� on Windows:
https://gitlab.haskell.org/ghc/ghc/-/blob/922c6bc8dd8d089cfe4b90ec2120cb4895...
And there��s a relevant issue: https://gitlab.haskell.org/ghc/ghc/-/issues/15670
Mizuki
2021/09/04 18:46��David James mailto:dj112358@outlook.com>��`��:
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.
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.
Also, I think the FloatFnInverses.hshttps://gitlab.haskell.org/ghc/ghc/-/blob/master/testsuite/tests/numeric/sho... 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).
Thanks again,
David.
From: arata, mizukimailto:minorinoki@gmail.com
Sent: 03 September 2021 13:43
To: David Jamesmailto:dj112358@outlook.com
Cc: haskell-cafe@haskell.orgmailto:haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] Trouble with asinh (c calls with Doubles) in Windows
Hi David,
If I understand correctly, GHC uses mingw-w64��s libc implementation on Windows.
Since mingw-w64��s math functions are not of very good quality, it is likely that asinh returns NaN for a very large input.
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.
As a note, you may get a different (compile-time computed) result for `asinh(x)` if you set a more aggressive optimization flag.
Mizuki
