> I have been using some of the functions of the classes Real and
> Fractional and I have observed that with the funcion
> "toRational" we can
> obtain the fraction that represents a given number. For instance:
> *P2> toRational (5.2::Float)
> 5452595 % 1048576
> Why we obtain this numbers instead of "52 % 10" or "26 % 5"?
Because you asked for the number to be converted to a Float first, and
5.2 can't be represented exactly in a single-precision float. If you
don't go via Float, you get the exact result:
Prelude> 5.2 :: Rational
26 % 5
> I have also obtained the following results with the functions
> "fromRational" and "toRational":
> *P2> (fromRational ((toRational 4) - ( toRational
> (5.2::Float) )))::Double
> -1.1999998092651367
> *P2> (fromRational ((toRational 4) - ( toRational
> (5.2::Double) )))::Double
> -1.2000000000000002
> *P2> (fromRational ((toRational 4) - ( toRational 5.2 )))
> -1.2000000000000002
> *P2> (fromRational ((toRational 4) - ( toRational
> (5.2::Float) )))::Float
> -1.1999998
These are all symptoms of rounding.
Cheers,
Simon
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