function [bonds,components] = rbg2abg(name,rbonds,rstrokes,rcomponents,\
				      port_coord,port_name,\
				      infofile,errorfile)

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %% Version control history
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %% $Id$
% %% $Log$
% %% Revision 1.35  1998/07/08 15:35:15  peterg
% %% Added errorfile argument
% %%
% %% Revision 1.34  1998/07/02 19:41:29  peterg
% %% Fixed empty port string bug - set to null string.
% %%
% %% Revision 1.33  1998/07/02 17:16:06  peterg
% %% Commented out redundent code -- obsolete due to new default mechanism
% %%
% %% Revision 1.32  1998/07/02 15:12:05  peterg
% %% Added hard error reporting
% %% Added error when two unlabled bonds point in.
% %%
% %% Revision 1.31  1998/07/02 14:30:50  peterg
% %% Corrected various bugs - including resettting n_ports to correct value
% %%
% %% Revision 1.30  1998/07/02 13:40:50  peterg
% %% Added extra ports names (due to defaults) to relevant lists:
% %% 	port_name
% %% 	port_bond
% %%
% %% Revision 1.29  1998/07/02 13:28:31  peterg
% %% Added defaults in new form BEFORE alias expansion
% %%
% %% Revision 1.28  1998/07/02 12:36:05  peterg
% %% Removed debugging lines
% %%
% %% Revision 1.27  1998/07/02 12:24:02  peterg
% %% Expand port aliases
% %%
% %% Revision 1.26  1998/04/16 14:07:51  peterg
% %% Sorted out [] problem with vector ports -- new octave function
% %% split_port
% %%
% %% Revision 1.25  1998/04/12 15:01:04  peterg
% %% Converted to uniform port notation - always use []
% %%
% %% Revision 1.24  1998/02/19 08:57:16  peterg
% %% Fixed mtt-info bug -- confused filename with number
% %%
% %% Revision 1.23  1997/12/04 14:24:22  peterg
% %% Removed error message about through-pointing arrows
% %%
% %% Revision 1.22  1997/09/18 19:49:37  peterg
% %% Added test for uniquness of bonds on a component -- if non-unique
% %% implies same component at both ends of a bond.
% %%
% %% Revision 1.21  1997/09/16  15:14:14  peterg
% %% Added warning if a component has no bonds.
% %%
% %% Revision 1.20  1997/08/18  19:39:48  peterg
% %% Now generates (exampaded) port_bond list correctely
% %%
% %% Revision 1.19  1997/08/14  11:59:47  peterg
% %% Vector ports added!!
% %%
% %% Revision 1.18  1997/08/14  11:01:42  peterg
% %% Reordered algorithms as follows:
% %% bond end coordinates
% %% associate port labels with bonds (port_bond)
% %% associate bonds with components
% %% unsorted list of bonds on each component (components)
% %% interpret strokes and setup the causality of the bonds (bonds)
% %% expand vector ports & add new bonds and connections
% %% sort bonds on each component according to the labels -- two ports
% %% default included here.
% %%
% %% Revision 1.17  1997/08/09 11:31:16  peterg
% %% Default two port list is [in;out] (or [out;in])
% %% Dont do global default if no ports labels.
% %%
% %% Revision 1.16  1997/08/07  16:12:36  peterg
% %% Fixed sorting bug: now puts the jth component from the unsorted list
% %% into the kth component of the sorted list .. not vice versa!
% %%
% %% Revision 1.15  1997/08/06  21:43:19  peterg
% %% Corrected error in creating component list: the kth component of the
% %% list is given by the jth component of the original list NOT vice
% %% versa.
% %%
% %% Revision 1.14  1997/08/04 14:18:55  peterg
% %% If no ports labels at all, just use the default component list.
% %%
% %% Revision 1.13  1997/08/04 12:50:39  peterg
% %% Many bug fixes to the named port version + tied up the logic and
% %% supporting comments.
% %%
% %% Revision 1.12  1997/08/02 19:37:53  peterg
% %% Now uses named ports.
% %%
% %% Revision 1.11  1997/04/29 09:12:37  peterg
% %% Added error message if port label near to >1 bond.
% %%
% %% Revision 1.10  1997/03/17  13:45:42  peterg
% %% Added more error info.
% %%
% %% Revision 1.9  1996/12/31  11:25:57  peterg
% %% Clearer error messages for incorrect ports.
% %%
% %% Revision 1.8  1996/12/04 21:52:39  peterg
% %% Now uses fopen.
% %%
% %% Revision 1.7  1996/11/01 18:01:57  peterg
% %% Rationalised port ordering.
% %% Fixed port bug.
% %%
% %% Revision 1.6  1996/08/25 08:27:14  peter
% %% Now checks ports correctely - I hope.
% %%
% %% Revision 1.5  1996/08/24 19:21:26  peter
% %% More specific error messages.
% %%
% %% Revision 1.4  1996/08/24 18:00:33  peter
% %% Fixed bug with finding ports.
% %%
% %% Revision 1.3  1996/08/09 08:26:35  peter
% %% Cosmetic tidy up.
% %%
% %% Revision 1.2  1996/08/04 18:37:57  peter
% %% Fixed  no causal strokes bug.
% %%
% %% Revision 1.1  1996/08/04 18:30:14  peter
% %% Initial revision
% %%
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%Default to no components
components = [0];

% Xfig scaling factor
scale = 1200.0/2.54546;

% Rotation matrix
rot = [0 -1; 1 0];

% Find number of strokes
[n_strokes,columns] = size(rstrokes);
if (columns ~= 4)&(n_strokes>0)
  error('Incorrect rstrokes matrix: must have 4 columns');
end;

% Find number of bonds
[n_bonds,columns] = size(rbonds);
if (columns ~= 6)&(n_bonds>0)
  error('Incorrect rbonds matrix: must have 6 columns');
end;

% Find number of components
[n_components,columns] = size(rcomponents);

% Find the number of ports refered to within the component
[n_ports,columns] = size(port_coord)

% If port_name is empty, make it a empty string
if (length(port_name)==0)
  port_name="";
end

% Determine coordinates of the arrow end of the bond and the other end
other_end_1 = rbonds(:,1:2);
arrow_end   = rbonds(:,3:4);
other_end_2 = rbonds(:,5:6);

distance_1   = length2d(other_end_1 - arrow_end);
distance_2   = length2d(other_end_2 - arrow_end);
which_end    = (distance_1>distance_2)*[1 1];
one          = ones(size(which_end));
other_end    = which_end.*other_end_1 + (one-which_end).*other_end_2;
arrow_vector = ( which_end.*other_end_2 + (one-which_end).*other_end_1 ) - ...
    arrow_end;
 
% Locate the bond end nearest to each port
% col 1 of port_near_bond contains a signed bond number (+ for arrow end)
% col 2  of port_near_bond contains the corresponding port index
port_bond = [];
for i = 1:n_ports
   near_bond = adjbond(port_coord(i,1:2),arrow_end,other_end);
   [rows,cols]=size(near_bond);
   if rows>1
     error(sprintf ...
	 ("A port is near to more than one bond at coordinates %g,%g\n", ...
	 port_coord(i,1)/scale,  port_coord(i,2)/scale));
   end;

  %The (signed) bond corresponding to the ith port label
  port_bond(i) = near_bond(1)*sign(1.5-near_bond(2));
end;
port_bond
%We now have the (signed) bond (port_bond(i)) correponding to the
% ith port label within the component 

% Locate the components at the ends of each bond
% col 1 of comp_near_bond contain the component nearest to the arrow end
% col 2 of comp_near_bond contain the component nearest to the other end
for i = 1:n_bonds
  comp_near_bond(i,:) = adjcomp(arrow_end(i,:),other_end(i,:),rcomponents);
end;
comp_near_bond
% We now have a list (comp_near_bond) of the component(s) at each end
% of each bond

% Now do a list of the bonds on each component - unsorted at this stage.
% Also expand aliases using the alias list for each component
components = [];
for i = 1:n_components
  %Get component type
  eval(['[comp_type, comp_name] = ', name, '_cmp(i)']);

  % There are n_comp_bonds bonds on this component with corresponding index
  [index,n_comp_bonds] = getindex(comp_near_bond,i);

  if index(1,1)==0
    mtt_error(sprintf("Component %s (%s) has no bonds", comp_name,
    comp_type),errorfile);
  end;
  
  % Create the signed list of bonds on this component
  one = ones(n_comp_bonds,1);
  bond_list = index(:,1); %  bond at component
  
  % Check that all bonds are unique -- error if not
  if unique(bond_list)==0
    mtt_error(sprintf("Component %s (%s) is at both ends of a bond", comp_name,
    comp_type),errorfile);
  end;
    

  % which end of bond at component?
  bond_end = index(:,2); 
  direction = -sign(bond_end-1.5*one);
  signed_bond_list = bond_list.*direction;
  components = add_bond(components,signed_bond_list',i);
  
  # Unalias all the ports on this component - if not a junction
  unlabelled_ports = 0;  
  in_bonds = 0;
  out_bonds = 0;
  if ((comp_type!="0")&&(comp_type!="1")) # Don't do junctions
    for j=1:n_comp_bonds
      signed_bond = signed_bond_list(j);
      port_name_index = getindex(port_bond,signed_bond);
      port_direction = sign(signed_bond);
      
      if port_name_index==0	# There is no port on this bond - so try
				# to default
	unlabelled_ports++;
	if(unlabelled_ports==1)
	  if port_direction>0
	    in_bonds++;
	    port_name_i = "in";
	  else
	    out_bonds++;
	    port_name_i = "out";
	  end;
	elseif (unlabelled_ports==2)
	  if port_direction>0
	    if (++in_bonds>1)
	      mtt_error(["More than one unlabelled INport on component " \
			comp_name " (" comp_type ")"],errorfile);
	    else
	      port_name_i = "in";
	    end
	  else
	    if (++out_bonds>1)
	      mtt_error(["More than one unlabelled OUTport on component " \
			comp_name " (" comp_type ")"],errorfile);
	    else
	      port_name_i = "out";
	    end
	  end;
	else
	  mtt_error(["More than two unlabelled ports on component " \
		    comp_name " (" comp_type ")"],errorfile);
        end
	mtt_info(["Defaulting port name [" port_name_i "]\t on component " \
		  comp_name " (" comp_type ")" ],infofile);
	port_name = [port_name; ["[" port_name_i "]"]];	# add to list
	[port_name_index,junk] = size(port_name); # the corresponding
				# index
	port_bond(port_name_index,:) = signed_bond; # add to port bond
      else  
      	port_name_i = deblank(port_name(port_name_index,:));
	port_name_i = port_name_i(2:length(port_name_i)-1) # strip []
      end;
      
      % Replace by alias -- if any
    	eval( ["alias = ", comp_type, '_alias';]); # Get aliases
    	if is_struct(alias)		# are there any aliases
          if struct_contains(alias,port_name_i) # Is this an alias?
	    eval(["new_port_name_i = alias.",port_name_i]);
	    mtt_info(["Aliasing name [" port_name_i "]\t on component " \
		      comp_name " (" comp_type ")\t to [" new_port_name_i "]"],infofile);
	    port_name = replace_name(port_name, \
				     ["[",new_port_name_i,"]"], \
				     port_name_index);
	  end
      	end
      end
    end
  end;
% At this point, every port should be labeled (port_name) and \
% associated with a bond (port_bond).
disp("--- Completed portnames and the corresponding bonds ---")
port_name, port_bond


% Deduce causality from the strokes (if any) and create the list of bonds
causality = zeros(n_bonds,2);
if n_strokes>0
  % Find out location of centre and ends of stroke.
  stroke_end_1 = [rstrokes(:,1) rstrokes(:,2)];
  stroke_end_2 = [rstrokes(:,3) rstrokes(:,4)];
  
  stroke_centre = (stroke_end_1 + stroke_end_2)/2;
  stroke_vector = (stroke_end_1 - stroke_end_2);
  stroke_length = length2d(stroke_vector);

% Deduce bond causality from the strokes 
  for i = 1:n_strokes
    stroke = [stroke_centre(i,:) 
    stroke_end_1(i,:)
    stroke_end_2(i,:)];


    % Find the nearest bond end.
    [index,distance] = adjbond(stroke(1,:),arrow_end,other_end);
    if (distance>2*stroke_length(i))
      info = sprintf('Stroke at (%4.3f,%4.3f) is %4.3f away from the nearest bond\n', ...
	stroke(1,1)/scale, stroke(1,2)/scale, distance/scale);
    end;
  
    % Bond end coordinates
    j = index(1,1);
    which_end = index(1,2)==1;
    bond_end = arrow_end(j,:)*which_end + other_end(j,:)*(1-which_end);
  
    % Now decide which bit of the stroke is nearest
    stroke_index = adjbond(bond_end,stroke,zeros(size(stroke)));
  
    if stroke_index(1)==1 % uni-causal stroke
      causality(j,1:2) = (2*which_end-1)*[1 1];
    else % bicausal stroke
      % Find out whether stroke is on flow side of bond
      stroke_direction = stroke(1,:) - stroke(stroke_index(1),:);
      flow_side = stroke_direction*arrow_vector(j,:)'>0;
      causality(j,1+flow_side) = 2*which_end-1;
    end;
  end;
end;

bonds = causality;

% Now expand vector ports
[n_bonds,junk] = size(bonds);
n_ports=length(port_bond);
n_exp_ports=n_ports;
exp_port_name="";
exp_port_bond = [];
%exp_comps = [];
for i=1:n_ports
  port_name_i = port_name(i,:)
  [subport,n_subports] = split_port(port_name_i, ','); % Find the components of the vector port

  if n_subports==1 % an ordinary port
    exp_port_name = [exp_port_name; subport(1,:)]; % Write out the only port
    exp_port_bond = [exp_port_bond; port_bond(i)]; % and the port_bond
  else % its a vector port
    % Check that there is a corresponding vector port at the other end of the
    % bond
    signed_bond_index = port_bond(i);
    [other_bond_index,n_other] = getindex(port_bond,-signed_bond_index);
    if n_other == 1
      other_port_name = port_name(other_bond_index,:);
      [other_subport,n_other_subports] = split_port(other_port_name, ',');
      if n_other_subports~=n_subports
	mtt_error(['Vector ports ', port_name_i, ' and ', other_port_name, 'are not compatible'],errorfile);
      end
    else 
      mtt_error(['Vector port ', port_name_i, ' has no matching port'], errorfile);
    end;
    
    if other_bond_index>i %then its not been done yet
      mtt_info(['Vector port: ', port_name_i],infofile);
      mtt_info(['matching: ', other_port_name],infofile);
      % Remove sign info.
      bond_index = abs(signed_bond_index);
      sig = sign(signed_bond_index);
      
      % Put the first element of each port list in the expanded list
      exp_port_name = [exp_port_name; subport(1,:)];
      exp_port_name = [exp_port_name; other_subport(1,:)];
      
      % Add to the expanded port_bond list
      exp_port_bond = [exp_port_bond; signed_bond_index; ...
	-signed_bond_index];
      
      % Add the other names to the expanded list and augment the bonds,
      % components and port_bond lists.
      for j=2:n_subports
	% Add a new name (for each end) to give a non-vector list
	exp_port_name = [exp_port_name; subport(j,:)];
	exp_port_name = [exp_port_name; other_subport(j,:)];
	      
	% Add one more bond to the list
	bonds = [bonds; bonds(bond_index,:)];
	n_bonds = n_bonds + 1;
      
	% Add bond to the expanded port_bond list (ports at both ends)
	exp_port_bond = [exp_port_bond; sig*n_bonds; -sig*n_bonds];


	% Add the new bond to the component at both ends (taking note 
	% of the direction).
	arrow_index = comp_near_bond(bond_index,1);
	components = add_bond(components, n_bonds, arrow_index);
	other_index = comp_near_bond(bond_index,2);
	components = add_bond(components, -n_bonds, other_index);
      end;
    end;
  end;
end;


%Replace old list by new
port_name = exp_port_name
port_bond = exp_port_bond

% Resize the lists
[n_ports,junk] = size(port_name);

port_name, components
% Produce a list of bonds on each component (within this component) 
%  - sorted if explicit port numbers
for i = 1:n_components    
  disp('-----------------');
  %Get component type
  eval(['[comp_type, comp_name] = ', name, '_cmp(i)']);

  %Convert junction names
  if comp_type=='0'
    comp_type = 'zero';
  end

  if comp_type=='1'
    comp_type = 'one';
  end

  % Find the (unsorted) bond list on this component
  signed_bond_list = nozeros(components(i,:));
  n_comp_bonds = length(signed_bond_list);
  direction = sign(signed_bond_list);
  
  %Find the port list for this component
  if exist([comp_type, '_cause'])==0
    eval(['[junk1,junk2,junk3,junk4,junk5,port_list]=', comp_type, '_rbg;']);
  else
    port_list=comp_ports(comp_type,n_comp_bonds);
  end;

  [n_comp_ports,m_comp_ports] = size(port_list);
  subport_list="";
  for p=1:n_comp_ports		# Expand any vector ports
    [subport,n_sub] = split_port(port_list(p,:), ','); # Find the components
						  # of the vector port
    if n_sub>1
      mtt_info(sprintf("Expanding vector port %s of component type %s",\
		       port_list(p,:), comp_type, infofile));	
    end;
    subport_list = [subport_list; subport];
  end;
  port_list = subport_list;	# Set the expanded port list.
  

  % Check that number of bonds on the component is the same as the number of
  % ports
  [n_comp_ports,m_comp_ports] = size(port_list);
  if (n_comp_ports~=n_comp_bonds) & ...
	~(strcmp(comp_type,'zero')|strcmp(comp_type,'one'))
    message=sprintf('Component %s (%s) has %1.0f impinging bonds but has %1.0f ports', ...
	comp_name,comp_type,n_comp_bonds,n_comp_ports);
    mtt_error(message, errorfile);
  end;
  
  unsorted_port_list="";
  if n_ports>0 % then there are some named ports
    % so find those associated with the bonds on this component.
    k=0; 
    for j = 1:n_comp_bonds
      b = signed_bond_list(j); 
      % Find the port label on component end of bond (if any)
      [port_index,m] = getindex(port_bond,b);
      if m==1
	k=k+1;
	unsorted_port_list(k,:) = port_name(port_index,:);
      end;
    end;
  else 
    k=0;
  end;
    
#  %Either all ports or no ports should be labelled - write error
#  %message if this is not so
#  if (k~=0)&(k~=n_comp_bonds)
#    mtt_info(['Component ', comp_name, ' (', comp_type, ') has wrong number of labels'], infofile); 
#    mtt_info(sprintf("\tit has %1.0f labels but should have 0 or \
#    %1.0f",k,n_comp_bonds), infofile);
#    portnames=""; 
#    for kk=1:k 
#      portnames=sprintf("%s %s",portnames, unsorted_port_list(kk,:));
#    end;
#    mtt_error(portnames,errorfile);
#  end;
  
  %Compute the number of labeled ports
  [n_unsorted_ports,m_unsorted_ports] = size(unsorted_port_list);
  if m_unsorted_ports==0
    n_unsorted_ports = 0;
  end;
#  n_unsorted_ports,n_comp_bonds
#  % One port defaults:
#  if (n_comp_bonds==1)&(n_unsorted_ports==0)
#    %if (direction(1)<0) & ~strcmp(comp_type,'SS') % Wrong way for default
#    % mtt_error(['One-port ', comp_name, ' (', comp_type, ') has the sign pointing the wrong way '], errorfile);
#    %end;
#    unsorted_port_list = port_list;
#  end;
  
#  %Two port defaults
#  if (n_comp_bonds==2)&(n_unsorted_ports==0)
#    if direction(1)==direction(2) % Wrong way for default
#      % mtt_error(['Two-port ', comp_name, ' (', comp_type, ') does not have through-pointing arrows'], errorfile);
#    end;
#    if direction(1)==1 %in
#      % mtt_info([comp_name, ' in'],infofile);
#      unsorted_port_list = ['[in]';'[out]'];
#    else %reverse the order
#      % mtt_info([comp_name, ' out'],infofile);
#      unsorted_port_list = ['[out]';'[in]'];
#    end;
#  end;
  
#  % Recompute the number of unsorted ports
#  [n_unsorted_ports,m_unsorted_ports] = size(unsorted_port_list);
#  if m_unsorted_ports==0
#    n_unsorted_ports = 0;
#  end;
  
  % Junctions or no lables(order of ports unimportant)
  if strcmp(comp_type,'zero')|strcmp(comp_type,'one')
    for j = 1:n_comp_bonds
      components(i,j) = signed_bond_list(j);
    end
  else %Order of ports is important
    unsorted_port_list, port_list
    if n_unsorted_ports==0
      mtt_error(['Component ', comp_name, ' (', comp_type, ') has no labeled ports'], errorfile); 
    end;
    %Write out the signed bond list in the correct order
unsorted_port_list
for j = 1:n_comp_bonds
      j
      name_k = unsorted_port_list(j,:)
      k = name_in_list(name_k, port_list);
      % Check that it only appears once in port list
      if length(k)>1
	mtt_error(['Component ', comp_name, ' (', comp_type, ') has ports with the same name:  ', name_k], errorfile); 
      end;
      
      %Check that it only appears one in the label list
      kk = name_in_list(name_k,unsorted_port_list);
      if length(kk)>1
	mtt_error(['Component ', comp_name, ' (', comp_type, ') has multiple port labels:  ', name_k], errorfile); 
      end;
      
      if k==0
	mtt_error(['Component ', comp_name, ' (', comp_type, ') has an unrecognised port: ', name_k], errorfile); 
      else
	components(i,k) = signed_bond_list(j);     
      end;
    end;
  end;
end;