On Nov 28, 2009, at 9:33 AM, Jason Rupert wrote:
By any chance is anyone aware of an R function that duplicates
Octave's poly function?
Here is a description of Octave's poly function:
Function File: poly (A)
If A is a square N-by-N matrix, `poly (A)' is the row vector of
the coefficients of `det (z * eye (N) - a)', the characteristic
polynomial of A. As an example we can use this to find the
eigenvalues of A as the roots of `poly (A)'.
roots(poly(eye(3)))
=> 1.00000 + 0.00000i
=> 1.00000 - 0.00000i
=> 1.00000 + 0.00000i
In real-life examples you should, however, use the `eig'
function for computing eigenvalues.
If X is a vector, `poly (X)' is a vector of coefficients of the
polynomial whose roots are the elements of X. That is, of C is a
polynomial, then the elements of `D = roots (poly (C))' are
contained in C. The vectors C andD are, however, not equal due
to sorting and numerical errors.
Thanks again for any insights and feedback.
RSiteSearch("characteristic polynomial")
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