on 02.04.2010 at 22:07 Scott McMurray wrote :
Actually, you *can* calculate with infinity. That's the reason for having it separate from NaN, and why it needs a sign. Any operation with NaN gives a NaN, but at least the following for Infs don't give NaNs (for any x, y where is_finite(x) && !is_nan(y)):
-(Inf) => -Inf -(-Inf) => Inf x + Inf => Inf x - Inf => -Inf x % Inf => x Inf + Inf => Inf -Inf - Inf => -Inf x < Inf => true x > -Inf => true y <= Inf => true y >= -Inf => true x / Inf => 0 x / -Inf => 0 if (y != 0) y * Inf => sign(y)Inf if (y != 0) y * -Inf => sign(-y)Inf
But the indeterminate forms do, of course, give NaNs:
Inf - Inf => NaN -Inf + Inf => NaN 0 * Inf => NaN 0 * -Inf => NaN Inf / Inf => NaN Inf / -Inf => NaN Inf % y => NaN
i can not imagine any circumstances under which this stuff would be useful can you? i see main applications of a big int lib as convenient implementation of crypto algorithms, compression algos and building an arbitrary precision floating (or fixed) point environment floating/fixed points built on top of a big int deal with infs and all that stuff beside the big int and remaining two cases don't need infs at all so what's on *your* mind? apart from that the presence of infs complicates things -- both the conception and the implementation -- Pavel P.S. if you notice a grammar mistake or weird phrasing in my message please point it out