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On 28.04.2010 16:40, Dan Zuras Intervals wrote:
And, if bigEnough is big enough to have tanh(bigEnough) = 1
in our working precision we have that:
tanh(Entire) = {[-1,1],{boundedTrue,boundedSticky}}
tanh(mostOfIt) = {[-1,1],{boundedTrue}}
So, like I said, it kind of depends on how you got there.
Both are obviously bounded final results but one used an
unbounded interval to get there.
And boundedSticky records that.
Nothing ominous in this case. But telling you that it
happened is the sticky's job.
I'm not sure on this one. I cannot construct an example where this fails out of my head, but my problems are along the following line.
The idea of the sticky part is to tell us after a series of operations that we encountered difficulties and that our result might be incorrect.
In the above example tanh(Entire) we know that the result of tanh is bounded irrelevant of what happened before. We keep the sticky part set and continue computations with ([-1,1],(boundedTrue, boundedSticky)). Even if we don't set boundedFalse again we'll arrive at some result with boundedSticky set. This says "look out, you cannot trust this result if you need boundedness". But in reality everything is fine since the tanh sort of got rid of the unbounded points (points for which boundedFalse is true). Aren't we throwing away good results this way?
I have the feeling that the somethingSticky property of an operation depends on the operation itself and shouldn't be set to
> 'thingy'Sticky = > 'thingy'False(xx) \or 'thingy'Sticky(xx) \or > 'thingy'False(yy) \or 'thingy'Sticky(yy) in all cases. Christian