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Re: The current proposal




VL> "Infinity as number" is buggy. For instance, with the above point of
VL> view, if F(x) = (x+1)-x, then F(Inf) = (Inf+1)-Inf = Inf-Inf = 0.

Under IEEE 754,  F(Inf) = (Inf+1)-Inf = Inf-Inf = NaN,  not 0.

- Ian McIntosh          Toronto IBM Lab   8200 Warden   D2-445   905-413-3411

----- Forwarded by Ian McIntosh/Toronto/IBM on 26/02/2009 12:03 PM -----
Vincent Lefevre <vincent@xxxxxxxxxx>

26/02/2009 11:57 AM
Please respond to
Vincent Lefevre <vincent@xxxxxxxxxx>

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Ian McIntosh/Toronto/IBM@IBMCA
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Re: The current proposal





>> This value is not even properly defined in many cases,
>> such as when F(x)=x-x or F(x)=(x-1)/(x+1) and A=[0,inf].
>
> If "infinity as number" is true, i.e., if the infinity is not a
> member of the interval but rather a token for an unbounded real
> number, then it is properly defined:
>
>    F(Inf)=Inf-Inf=0
>    F(Inf)=(Inf-1)/(Inf+1)=Inf/Inf=1
>
> Nate Hayes
> Sunfish Studio, LLC

"Infinity as number" is buggy. For instance, with the above point of
view, if F(x) = (x+1)-x, then F(Inf) = (Inf+1)-Inf = Inf-Inf = 0.

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Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.org/>
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Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)