On Tue, Mar 27, 2001 at 09:26:15AM -0800, Peter Buckingham wrote:
> I x A = I x A x A
> A = A^2
Problem with this: A isn't a matrix, nor is it even a vector (in the big
sense, not the pointy-arrow). It isn't that simple. Also, idempotent in
the CS world is diferent then in the algeberic world (and functions aren't)
-- f(f(x)=f(x) isn't the criteria for idempotency, f(a) is equal to f(a) in
result for any a, and for any state not embodided in a, and the state not
embodied in the return of the function does not change.
> So it would be easy if we could have an identity data element on hand, but
> even if we don't it is pretty unlikely that the data element will special
> enough to make the above true (substitute the data element for I).
Not so much. Say the transform, f, is to trim any non-digits from the input.
f("+123,456")=123456
f(f("+123,456))=123456
The functon is not idempotent. Even if you checked f(x)==x (function is the
identity), an input of "123456" would work.
-=- James Mastros
--
The most beautiful thing we can experience is the mysterious. It is the
source of all true art and science. He to whom this emotion is a stranger,
who can no longer pause to wonder and stand wrapt in awe, is as good as dead.
-=- Albert Einstein
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