Float precision and float equality

[TheSeeker]

On Dec 6, 4:54 pm, Carl Banks <pavlovevide... at gmail.com> wrote:
> On Dec 6, 11:34 am, Anton81 <gerenu... at googlemail.com> wrote:
>
> > I do some linear algebra and whenever the prefactor of a vector turns
> > out to be zero, I want to remove it.
>
> > I'd like to keep the system comfortable. So basically I should write a
> > new class for numbers that has it's own __eq__ operator?
> > Is there an existing module for that?
>
> I highly recommend against it; among other things it invalidates the
> transitive property of equality:
>
> "If a == b and b == c, then a == c."
>
> It will also make the number non-hashable, and have several other
> negative consequences.    What numbers are close enought to be condidered "equal"
> depends on the calculations.
>
> (I remember once struggling in a homework assignment over seemingly
> large discrepancies in a calculation I was doing, until i realized
> that the actual numbers were on the scale of 10**11, and the
> difference was around 10**1, so it really didn't matter.)
>
> Carl Banks

Maybe it's the gin, but
"Plus, it's not something that's never foolproof.'

+1 QOTW

Cheers,
TheSeeker