Compute zeros of simple quaternionic polynomials

Compute the zeros of a polynomial with quaternion coefficients and quaternion variable.

% Compute the zeros of a polynomial with quaternion coefficients and

% quaternion variable. The algorithm is due to [1]. This code computes all

% the zeros, but does not implement the part where we can also determine

% whether the zero is isolated or spherical.

%

% [1] Drahoslava Janovsk´a and Gerhard Opfer. “A Note on the Computation

% of All Zeros of Simple Quaternionic Polynomials”. In: SIAM Journal on

% Numerical Analysis 48.1 (2010), pp. 244–256. doi: 10.1137/090748871.