function h_matrix = rri_helmert_matrix(num_rows)
%
% USAGE:  helmert_matrix = rri_helmert_matrix(num_rows)
%
%   Generate the Helmert matrix with a given row size
%

  nc = num_rows-1;
  nr = num_rows;

  c = zeros(nr,nc);
  for i=1:nc;
     c(i,i) = num_rows-i;
     c(i+1:nr,i) = -1;
  end;

  norm_len = sqrt(sum(c .^ 2));
  for i=1:num_rows-1;
     h_matrix(:,i) =  c(:,i) / norm_len(i);
  end;

  return;					% rri_helmert_matrix