[Haskell-cafe] Little errors in number calculations

[Lennart Augustsson]

Hugs is wrong, as you can easily see by evaluating
   let x = 123.35503 * 10.0 in x == read (show x)
With ghc it comes out as True and with Hugs as False.

  -- Lennart

On Sat, Nov 14, 2009 at 9:00 PM, Abby Henríquez Tejera
<paradoja at gmail.com> wrote:
> Hi.
>
> I've seen that in GHC sometimes there are little errors in some basic
> number calculations:
>
> *Prelude> 123.35503 * 10.0
> 1233.5502999999999
>
> *Prelude> properFraction 123.35503
> (123,0.3550299999999993)
>
> whereas in Hugs no such errors seem to occur (that I have found, at
> least):
>
> *Hugs> 123.35503 * 10.0
> 1233.5503
>
> (but:)
>
> *Hugs> properFraction 123.35503
> (123,0.355029999999999)
>
> I understand that error may (and will) happen in floating point, but
> it surprises me that they do so easily, and, above all, the difference
> between GHC and Hugs. Does someone know why does this difference
> occur?
>
> (Thanks in advance, by the way :) ).
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