% -*- texinfo -*-
% @deftypefn {Function File} {} hankel (@var{c}, @var{r})
% Return the Hankel matrix constructed given the first column @var{c}, and
% (optionally) the last row @var{r}. If the last element of @var{c} is
% not the same as the first element of @var{r}, the last element of
% @var{c} is used. If the second argument is omitted, it is assumed to
% be a vector of zeros with the same size as @var{c}.
%
% A Hankel matrix formed from an m-vector @var{c}, and an n-vector
% @var{r}, has the elements
% @tex
% $$
% H (i, j) = \cases{c_{i+j-1},&$i+j-1\le m$;\cr r_{i+j-m},&otherwise.\cr}
% $$
% @end tex
% @ifnottex
%
% @example
% @group
% H(i,j) = c(i+j-1), i+j-1 <= m;
% H(i,j) = r(i+j-m), otherwise
% @end group
% @end example
% @end ifnottex
% @seealso{vander, sylvester_matrix, hilb, invhilb, toeplitz}
% @end deftypefn