function seqwrite(X,outfile,opts)

% SEQWRITE writes from a sequence object
%  seqwrite(X,outfile,opts)
%
% opts.flat  : 0 if sequential (default) 1 if flat 
% opts.sparse : 0 if dense and 1 if sparse (default)
% opts.sep : 0 if space separated (default), 1 if tag separated
% opts.useoriglabels : 0 if not, 1 if so (default)
% opts.dimheader : 0 if want to use it, 1 if not 
%    current default is to set it to 1-opts.flat 

if nargin<3,opts.seq=1;end
if ~isfield(opts,'flat'),opts.flat=0;end
if ~isfield(opts,'sparse'),opts.sparse=1;end
if ~isfield(opts,'sep'),opts.sep=0;end
if ~isfield(opts,'useoriglabels'),opts.useoriglabels=1;end
if ~isfield(opts,'dimheader'),opts.dimheader = ~opts.flat;end


fid = fopen(outfile,'wt');
numseq = length(X.labels);
DIM=size(X.data{1},2);

if opts.dimheader
  fprintf(fid,'<dimension=%d>\n',DIM);
end

for k=1:numseq
  [N,D] = size(X.data{k});
  if opts.sparse
    [Xi,Xj,Xv] = find(X.data{k});
  end 
  if D~=DIM
    error(sprintf('dimension %d of X.data{%d} not equal to dimension %d of X.data{1}',D,k,DIM));
  end
  if ~opts.flat
    if (opts.sep==1)
      fprintf(fid,'<sequence length=%d>\n',N);
    elseif k>1
      fprintf(fid,'\n');
    end
  end
  
  for n=1:N
    if (opts.useoriglabels)
      fprintf(fid,'%d ',X.origlabels(X.labels{k}(n)));
    else
      fprintf(fid,'%d ',X.labels{k}(n));
    end
    if opts.sparse
      f = find(Xi==n);
      for i=1:length(f)
         fprintf(fid,'%d:%f ',Xj(f(i)),Xv(f(i)));
      end
    else
      for d=1:DIM
	fprintf(fid,'%f ',X.data{k}(n,d));
      end
    end
    fprintf(fid,'\n');
  end
  
  if ~opts.flat
    if (opts.sep==1)
      fprintf(fid,'</sequence>\n',N);
    end
  end
  
end