Re: [Scheme-reports] Strong win later reversed: Real numbers have imaginary part #e0

[Alex Shinn <alexshinn@x>]

On Mon, Dec 24, 2012 at 3:25 PM, Mark H Weaver <mhw@x> wrote:

Alex Shinn <alexshinn@x> writes:

> On Mon, Dec 24, 2012 at 7:51 AM, Mark H Weaver <mhw@x> wrote:
>

>     What external representation will you use for these numbers?  For
>     example, even if you can efficiently handle something like this:
>
>       (do ((i 10000000 (- i 1))
>            (x 1e300 (expt x x)))
>           ((zero? i) (/ x)))
>
>     What will you do if someone applies 'number->string' to the
>     result?
>
> It will use Conway's chained arrow notation, as mentioned
> in my previous mail.
>
> What you're describing here is just tetration:
>
>   (tetrate 1e300 100000000)

That's not quite right, but anyway the precise value of this number is
not relevant to my point.  My question was about how such numbers would
be printed, and your answer was that it might look something like this:

>   1/1e300->1e7->2

My point is that the results of ordinary inexact numerical computations
that are printed 0.0 on virtually every other system will apparently be
printed in a non-standard notation in future Chibi.

Yes, precisely, where normal implementations will produce

+inf.0 or -0.0, chibi will produce finite non-zero values.

In all other cases, numbers in chibi will be normalized to

produce the same output as other implementations.  Thus

the difference only arises when IEEE has already

over/underflowed and is giving infinitely incorrect values.

This is purely a win.

-- 

Alex

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