[Maxima] Representation of floats

[Evgeniy Maevskiy]

Thanks to all. Yes, it is the fact: 

numer:false$
is(0.2=1/5);  /* false - it's clear */

numer:true$
is(0.2=1/5); /* true - and it's clear too */

Now I'd like to compute the error:

numer:false$
0.2-1/5;

returns 0.0 

I think that the error must be about 1e-16. Can I compute it explicitly?