[R] bug when subtracting decimals?

[Petr PIKAL]

r-help-bounces at r-project.org napsal dne 21.04.2009 10:00:06:

> Petr PIKAL <petr.pikal <at> precheza.cz> writes:
> 
> > Maybe that is because of Excel is so widespread now and gives expected 

> > results (it probably silently rounds all decimal numbers before 
> > calculation). 
> 
> Marc Schwartz already reminded me of that one, and it's a good point
> to explicitly mention in lectures. 
> 
> I suggest to extend R by introducing %==% as "being Excellently equal".

It helps but not in all cases

> (0.7-0.3)-.4>0
[1] FALSE
> (0.7-0.3)-.4<0
[1] TRUE
>

There always could be different issues with not exact representation of 
decimals. So educated user or internal rounding could help but I am not 
sure if later is desired.

Regards
Petr

> 
> Dieter
> 
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