Re: Polynomial Roots
On Sun, 19 Aug 2007 03:39:22 -0400, "Jon G." <jon8338@peoplepc.com>
wrote:
>http://mypeoplepc.com/members/jon8338/polynomial/
It's wrong after just a few steps.
You start with the equation to be solved
(1) a_0 + a_1*t + a_2*t^2 + ... + a_n*t^n = 0
You rewrite (1) as a dot product of vectors ...
(2) P_1 . T = 0 where
P = <a_0, a_1, a_2, ..., a_n>
and
T = <1, t, t^2, ..., t^n>
So far, no problem.
You then note that the 2-vector <a_0, a_p> is perpendicular to the
2-vector <-a_p/a_0, 1>. Fine.
You then make the false claim
(3) <1, t^p>/(1 + t^(2p)) = <-a_p, a_0>/((a_0)^2) + (a_p)^2)
Although you neglect to use _words_ to defend your claim, I can guess
what your flawed reasoning probably was ...
Since the vectors P_1, T are perpendicular, you concluded that they
must be perpendicular when restricted to pairs of components.
There's no way to justify that.
Here's a counterexample ...
Consider the equation
-3 + t + t^2 + t^3 = 0
which has the obvious solution t=1.
Thus, the vector equation is
<-3, 1, 1, 1> . <1, 1, 1, 1> = 0
But there is no perpendicular pair of corresponding components, which
is what you claimed.
Thus, your "solution" is simply bogus.
Don't you think you should have checked a few examples before
launching into the monstrosity you posted?
quasi
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