On Sat, Nov 14, 2009 at 09:00:42PM +0000, Abby Henríquez Tejera wrote:

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?

The inaccuracy of floating point is the issue; it's just that Hugs sometimes prints things with less precision than required by the Haskell Report, and this can hide the errors.

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 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 :) ). _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe