% -*- texinfo -*-
% @deftypefn {Function File} {[@var{xinf}, @var{x_ha_err}] =} hinfsyn_ric (@var{a}, @var{bb}, @var{c1}, @var{d1dot}, @var{r}, @var{ptol})
% Forms
% @example
% xx = ([bb; -c1'*d1dot]/r) * [d1dot'*c1 bb'];
% Ha = [a 0*a; -c1'*c1 - a'] - xx;
% @end example
% and solves associated Riccati equation.
% The error code @var{x_ha_err} indicates one of the following
% conditions:
% @table @asis
% @item 0
% successful
% @item 1
% @var{xinf} has imaginary eigenvalues
% @item 2
% @var{hx} not Hamiltonian
% @item 3
% @var{xinf} has infinite eigenvalues (numerical overflow)
% @item 4
% @var{xinf} not symmetric
% @item 5
% @var{xinf} not positive definite
% @item 6
% @var{r} is singular
% @end table
% @end deftypefn