Hey Barak, is Common Lisp the only extant language to take those issues
seriously or are there other examples or better ones?
(i bought the common lisp book a year or so ago because its one of the few
references i could that talk about language/ library design for numerics /
branch cuts etc)
please edumacate me :)
-Carter
On Fri, Sep 17, 2021 at 12:18 PM Barak A. Pearlmutter
The numerics in Haskell have not been carefully vetted, for a variety of reasons. Not just under MS Windows, even under Linux. Here's an example: atan has drastic loss of precision in the imaginary direction around zero in the complex domain.
$ ghci GHCi, version 8.8.4: https://www.haskell.org/ghc/ :? for help Prelude> :m + Data.Complex
Prelude Data.Complex> tan (1e-20 :+ 0) 1.0e-20 :+ 0.0
Prelude Data.Complex> atan (1e-20 :+ 0) 1.0e-20 :+ (-0.0)
Prelude Data.Complex> tan (0 :+ 1e-20) 0.0 :+ 1.0e-20
Prelude Data.Complex> atan (0 :+ 1e-20) 0.0 :+ (-0.0)
Although there have been amazing efforts to use fancy PLT methods to improve the numerics of programs using source-to-source transformations and such, the boring janitorial work of checking and fixing numeric issues in the standard library doesn't seem to attract people. To be fair, it isn't my cup of tea either... _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.