[racket-dev] [plt] Push #28633: master branch updated

On 04/27/2014 05:14 PM, mflatt at racket-lang.org wrote:
>
> ~~~~~~~~~~
>
> d682c94 Matthew Flatt <mflatt at racket-lang.org> 2014-04-27 13:58
> :
> | repairs to precision of `exact->inexact` et al.
> |
> | Thanks to Neil T.!
> :
>    M racket/src/racket/src/numarith.c                  | 28 ++++++--
>    M racket/src/racket/src/ratfloat.inc                | 74 +++++++++++++++-----
>    M racket/src/racket/src/rational.c                  | 11 +++
>    M racket/src/racket/src/schpriv.h                   |  2 +
>    M .../racket-test/tests/racket/number.rktl          | 53 ++++++++++++++
>
> ~~~~~~~~~~
>
> 04c4538 Matthew Flatt <mflatt at racket-lang.org> 2014-04-27 15:17
> :
> | speed up `inexact->exact`
> |
> | Parse IEEE floating-point numbers directly.
> |
> | Thanks to Neil T.!
> :
>    M racket/src/racket/sconfig.h                       |   3 +
>    M racket/src/racket/src/numstr.c                    | 177 ++++++++++++-------
>    M racket/src/racket/src/ratfloat.inc                |  73 +++++++-
>    M racket/src/racket/src/rational.c                  |  18 +-
>    M racket/src/racket/src/schpriv.h                   |   2 +
>    M .../racket-test/tests/racket/number.rktl          |  33 +++-

Thanks for translating these into C so quickly! My plane-line 
intersection test cases run about twice as fast now, and because 
`exact->inexact` is correctly rounded, I can set the error reporting 
threshold to 0.5 ulps.

Strange thing, though: while `inexact->exact` is now about 10x faster, 
my TR implementation `flonum->rational` is now about 7x slower. I've 
verified that `flonum->fields` accounts for about 85% of the running 
time. I see that you've changed `integer-bytes->integer`, which 
`flonum->fields` uses. Could it have been a pessimization on certain 
platforms?

Neil ⊥