Floating point problems

[Lennart Augustsson]

Slightly tongue in cheek, I think the real problem is that your  
courses come in the wrong order.  No one should use floating point  
numbers without first having a course in numerical analysis. :)

	-- Lennart

On Aug 30, 2006, at 14:38 , Jamie Brandon wrote:

> I recently defied my supervisor and used Haskell to write my  
> coursework
> instead of C. All went well until I needed floating point and
> started having odd results. As far as I can tell it isn't
> substantially affecting my results but it is rather embarrassing after
> slagging off C so much. Here are some examples:
>
>         *Main> 0.2 + 0.1
>         0.30000000000000004
>         *Main> 0.200000000000000 + 0.100000000000000000
>         0.30000000000000004
>         *Main> 0.3 + 0.1
>         0.4
>         *Main> 0.2 + 0.1
>         0.30000000000000004
>         *Main> it + 0.1
>         0.4
>
> I assume this is a result of the discrepancy between binary and  
> decimal
> representations of the numbers. Is there any way around? For a  
> start, it
> would be nice to have a simple way to get 0.1 + 0.2 == 0.3  =  True
>
> This is with GHC 6.4.1 and GCC 4.0.3
>
> Thanks, Jamie
>
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