bug when subtracting decimals?

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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bug when subtracting decimals?

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