XMP, Krita, KFileMetaInfo and Strigi

[Tobias G. Pfeiffer]

Hi!

On Friday 22 June 2007, 19:09, Jos van den Oever wrote:
> 2007/6/22, Cyrille Berger <cberger at cberger.net>:
> > > >  - it lacks some important types like rationals
> > >
> > > a double is not a rational? QVariant::Double
> >
> > Yes it is, but a rational isn't a double, it's a division between two
> > integers.
> > For instance, there is no double representation of the rational 2 / 3
> > (0.66666666666666666666666666666666 is just an approximation, even if the
> > mathematical theory says that 0.666 followed only by 6 is equal to 2 / 3,
> > but there is no way to represent such a thing in double, 2/3 is
> > represented by 0.666..67 in a double anyway).
>
> It is very simple and not expensive to find a nice rational from a
> double.

What do you mean by "not expensive"? And what by "nice"? For every number that 
is stored as a double, there are infinitely many rational numbers that give 
that result. With both numerator and denominator being represented by a 
finite number of bits, you end up with a finite number of possible 
combinations, yeehaw. Now you don't even want to find a rational that has the 
same value as this double, but something "nice" that has a *similar* value as 
the given double. (Funny: look at 1.001002004008016032064128256, which might 
look very constructed, with powers of 2, but is actually the result of 
999/998, continuing with digits 513 = 512 + 001024 etc.) -- Maybe this is a 
bit academic, but it seems to me as if storing a pair of integers is waaaay 
less problematic than trying to recreate such a representation from a double.

Bye
Tobias

-- 
follow the penguin...
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