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        polyroot(z)

   AArrgguummeennttss::

          z: the vector of polynomial coefficients in decreas-
             ing order.

   DDeessccrriippttiioonn::

        A polynomial of degree n - 1,

               p(x) = z1 + z2 * x + ... + z[n] * x^(n-1)

        is given by its coefficient vector `z[1:n]'.  `poly-
        root' returns the n-1 complex zeros of p(x) using the
        Jenkins-Traub algorithm.

   VVaalluuee::

        A complex vector of length n - 1, where n is
        `length(z)'.

   RReeffeerreenncceess::

        Jenkins and Traub (1972).  TOMS Algorithm 419.  Comm.
        ACM 15, 97-99.

   SSeeee AAllssoo::

        `uniroot' for numerical root finding of arbitrary func-
        tions; `complex' and the `zero' example in the demos
        directory.

   EExxaammpplleess::

        polyroot(c(1, 2, 1))
        round(polyroot(choose(8, 0:8)), 11) # guess what!
        for (n1 in 1:4) print(polyroot(1:n1), digits = 4)

