Subject: RE: conjugate poles/zeros for the laplace and zi
From: Ian Wilson (imw@antrim.com)
Date: Tue Feb 27 2001 - 17:10:16 PST
>
> By the way, I don't think having conjugates automagically completed is
> a good idea. If two roots are almost conjugates, we get in the game of
> guessing whether they really are conjugates or are each half of a pair
> to be completed. It is much clearer to error off and let the user be
> explicit.
>
I think we would all agree with this. The problem with the current scheme
(and what I believe Martin is looking for resolution on) is how to tell when:
(a0 + jb0), (a1 + jb1) ...... (1)
are intended to be conjugates. (Under the current scheme it's an error
if the conjugate isn't found; under an automagical completion scheme this
would specify 2 distinct roots).
My opinion for what it's worth is that the answer to (1) above is that
the the two form a conjugate pair when a0-a1 and b0+b1 are both zero to
IEEE floating point precision (i.e. the presence of a root and its
conjugate is a synbolic indication, not a numerical one).
If we are looking for a better syntax in the future, I'd like one that:
- specifies whether a root is real or complex;
- specifies whether a root is degenerate and if so, its degree
--ian
--ian
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