accuracy of asinh and atanh

George Colpitts george.colpitts at
Wed Aug 1 19:13:03 UTC 2018

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.



On Sat, Jun 2, 2018 at 2:23 AM Matt Peddie <mpeddie at> 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
> -- 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 at
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