If A is a square N-by-N matrix,
is the row vector of the coefficients of
det (z * eye (N) - A),
the characteristic polynomial of A. For example,
the following code finds the eigenvalues of A which are the roots of
roots (poly (eye (3))) ⇒ 1.00001 + 0.00001i 1.00001 - 0.00001i 0.99999 + 0.00000i
In fact, all three eigenvalues are exactly 1 which emphasizes that for
numerical performance the
eig function should be used to compute
If x is a vector,
poly (x) is a vector of the
coefficients of the polynomial whose roots are the elements of x.
That is, if c is a polynomial, then the elements of
roots (poly (c)) are contained in c. The vectors c and
d are not identical, however, due to sorting and numerical errors.
See also: roots, eig.
Write formatted polynomial
c(x) = c(1) * x^n + … + c(n) x + c(n+1)
and return it as a string or write it to the screen (if nargout is
zero). x defaults to the string
See also: polyreduce.
Reduce a polynomial coefficient vector to a minimum number of terms by stripping off any leading zeros.
See also: polyout.