Re: sumskipnan(nan) = 0 ?

[Søren Hauberg]

address@hidden skrev:
> sum(A) + sum(empty) = sum(A) + nan = sum(A). No?
>
> To me, the only reasonable choice for the sum of nothing is nothing, that is:
>
> sum(nan) = nan.
I think you are misunderstanding the meaning of NaN. "NaN" means "Not a 
Number", so the addition of "a number" and "not a number" is really well 
defined. That is NaN+1 can't be a number, and hence must be NaN. Your 
arguments could to some extend work for "NA" (that is "Not Available"), 
but even then I wouldn't agree with your logic.

Søren