  Quaternions, introduced by Hamilton in 1843 as a generalization of complex
numbers, have found, in more recent years, a wealth of applications in a number
of different areas which motivated the design of efficient methods for
numerically approximating the zeros of quaternionic polynomials. In fact, one
can find in the literature recent contributions to this subject based on the
use of complex techniques, but numerical methods relying on quaternion
arithmetic remain scarce. In this paper we propose a Weierstrass-like method
for finding simultaneously {\sl all} the zeros of unilateral quaternionic
polynomials. The convergence analysis and several numerical examples
illustrating the performance of the method are also presented.
