[Haskell-cafe] Error with Float
Cale Gibbard
cgibbard at gmail.com
Tue Jul 19 11:00:34 EDT 2005
Perhaps you mean:
f x
| x < 1 = 0 : f (2*x)
| otherwise = 1 : f (2*(x-1))
Note that in the second case, the 1 is subtracted before multiplication by 2.
If you were referring to the problem that this eventually gives
constantly 0 for values like 0.6, try importing the Ratio module and
applying it to 6%10, which is the exact rational value rather than a
floating point representation.
- Cale
On 19/07/05, Dinh Tien Tuan Anh <tuananhbirm at hotmail.com> wrote:
>
> This is my function to convert a fraction (0<x<1) to binary :
>
> f x
> ¦t<1 = 0::f t
> ¦otherwise = 1::f (t-1)
> where t = 2*x
>
>
> I guess there's nothing wrong with that, but when traced, it has something
> like 0.6*2 - 1 = 0.600001
> This error got accumulated and made my f function wrong (will eventually
> evaluate an infinite 0, no matter what value of x)
>
> Please tell me there's some ways to deal with that.
>
> Thanks a lot
>
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