[Rd] Hyperbolic tangent different results on Windows and Mac

[Jeroen Ooms]

For future reference:
https://sourceforge.net/p/mingw-w64/mailman/message/35747206/

On Wed, Mar 22, 2017 at 2:12 PM, Jeroen Ooms <jeroenooms at gmail.com> wrote:
> This looks like a bug in mingw-w64 CRT. The problem can be produced
> with C++ without R:
>
>   #include <iostream>
>   #include <cmath>
>   #include <complex>
>
>   int main(){
>     std::cout << std::fixed;
>     std::complex<double> z(356, 0);
>     std::cout << "tanh" << z << " = " << std::tanh(z)
>          << " (tanh(356) = " << std::tanh(356) << ")\n";
>   }
>
> On OS-X we get:
>
>   tanh(356.000000,0.000000) = (1.000000,-0.000000) (tanh(356) = 1.000000)
>
> But on Windows we get:
>
>   tanh(356.000000,0.000000) = (nan,0.000000) (tanh(356) = 1.000000)
>
> I was also able to reproduce the problem with gcc 6.3 in msys2 so it
> has not been fixed upstream. You should file a bug report for
> mingw-w64.
>
> FWIF, we have run into NaN edge-case bugs before with mingw-w64.
>
>  - https://sourceforge.net/p/mingw-w64/mingw-w64/ci/6617ebd5fc6b790c80071d5b1d950e737fc670e1/
>  - https://github.com/wch/r-source/commit/e9aaf8fdeddf27c2a9078cd214a41475c8ff6f40
>
> I am cc'ing Ray Donnelly who is an expert on mingw-w64.