Re: accuracy of asinh and atanh

Hi George, Not a stupid question. I don't have a single source at hand, but I think I read in a few places on the wiki that calling out to the system math library is not an option due to the variety of system math libraries on the platforms GHC supports. It'd be great if I got the wrong impression and this could just be a call to C. Can anyone set me straight on this point? Matt On Thu, Aug 2, 2018 at 5:13 AM, George Colpitts wrote:

Hello Mat

Just curious, why the preferred solution isn't to call the system math library? As it says in the README you reference below,

One good solution would be to always call the system math library for these functions.

Hope this is isn't a stupid question.

Thanks

George

On Sat, Jun 2, 2018 at 2:23 AM Matt Peddie wrote:

...

Hi devs,

I tried to use asinh :: Double -> Double and discovered that it's inaccurate compared to my system library (GNU libm), even returning -Infinity in place of finite values in the neighborhood of -22 for large negative arguments. `atanh` is also inaccurate compared to the system library. I wrote up a more detailed description of the problem including plots in the README file at https://github.com/peddie/ghc-inverse-hyperbolic -- this repository is package that can help you examine the error for yourself or generate the plots, and it also contains accurate pure-Haskell translations of the system library's implementation for these functions. What's the next step to fixing this in GHC?

Cheers

Matt Peddie _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs