plconv(trt,trr,epsl,endloop,tit,ylab,nx,nc,b);

% PLCONV: Plot convergence results
%
%         plconv(trt,trr,epsl,endloop,tit,ylab,nx,nc);
%
%         trt    : trace array to be plotted
%         trr    : relative trace
%         epsl   : epsilon that determines convergence
%         endloop: switch that determines title
%         tit    : String for title
%         ylab   : ylabel string
%         nx     : Full-order (optional with nc)
%         nc     : Reduced-order (optional with nx)
%
%         L.G. Van Willigenburg, W.L. De Koning 01-07-96
%
  function plconv(trt,trr,epsl,endloop,tit,ylab,nx,nc,b);

% parameter that determines the length
% of the final part of trt which is plotted
  lplot=51;

  ltrt=length(trt);
  if ltrt>=lplot;
    xmin=ltrt-lplot+1; xmax=ltrt;
    trt=trt(xmin:xmax);
  else;
    xmin=1; xmax=ltrt;
  end

  xp=0.1*(xmax-xmin)+xmin;
  ymax=max(trt); ymin=min(trt);

  if (ymax-ymin)/(ymax+ymin)<1e-3
    trt=trt(1)*ones(1,max(size(trt)));
  end;

  if (ymax-ymin)/(ymax+ymin)<2e-2
    ymax=ymax+0.01*abs(ymax)+1e-2;
    ymin=ymin-0.01*abs(ymin)-1e-2;
  end;

  if nargin>6 ext1=1.3; ext2=1.2; ext3=1.1;
  else; ext1=1.2; ext2=1.1; end;

  plot(xmin:xmax,trt);

%  if xmin>=xmax; keyboard; end;
%  if ymin>=ymax; keyboard; end;

  axis([xmin xmax ymin ymin+ext1*(ymax-ymin)]);
  stri=['Convergence when ' num2str(trr) ' < ' num2str(epsl)];
  yp=ymin+ext2*(ymax-ymin);
  text(xp,yp,0,stri);
 
  if nargin>6;
    stri=['Full-order=' num2str(nx) '    Reduced-order=' num2str(nc)];
    if nargin>8; stri=[stri '  b=' num2str(b)]; end;
    yp=ymin+ext3*(ymax-ymin); text(xp,yp,0,stri);
  end;

  xlabel('Iteration number'); ylabel(ylab);
  if endloop==1;
    stri=[tit ': Final convergence plot'];
  else
    stri=[tit ': Intermediate convergence plot'];
  end
  title(stri); figure(gcf); drawnow;