tzero

% -*- texinfo -*-
% @deftypefn {Function File} {[@var{zer}, @var{gain}] =} tzero (@var{a}, @var{b}, @var{c}, @var{d}, @var{opt})
% @deftypefnx {Function File} {[@var{zer}, @var{gain}] =} tzero (@var{sys}, @var{opt})
% Compute transmission zeros of a continuous system:
% @iftex
% @tex
% $$ \dot x = Ax + Bu $$
% $$ y = Cx + Du $$
% @end tex
% @end iftex
% @ifinfo
% @example
% .
% x = Ax + Bu
% y = Cx + Du
% @end example
% @end ifinfo
% or of a discrete one:
% @iftex
% @tex
% $$ x_{k+1} = Ax_k + Bu_k $$
% $$ y_k = Cx_k + Du_k $$
% @end tex
% @end iftex
% @ifinfo
% @example
% x(k+1) = A x(k) + B u(k)
% y(k)   = C x(k) + D u(k)
% @end example
% @end ifinfo
% 
% @strong{Outputs}
% @table @var
% @item zer
%  transmission zeros of the system
% @item gain
% leading coefficient (pole-zero form) of @acronym{SISO} transfer function
% returns gain=0 if system is multivariable
% @end table
% @strong{References}
% @enumerate
% @item Emami-Naeini and Van Dooren, Automatica, 1982.
% @item Hodel, @cite{Computation of Zeros with Balancing}, 1992 Lin. Alg. Appl.
% @end enumerate
% @end deftypefn