%
% NICHLS  NICHLS is the M-file which is used to plot the
%         Nichols Chart for the given system or systems.
%

%    Author:  Ole Barup Sorensen, Rapid Data Ltd 

%    Copyright (c) 1989-94 by Rapid Data Ltd
%    Revision 11:12  05/10/94

okflag=figflag(tit1,0);

if okflag==0
  Fig17=figure('Numbertitle','off','Name',tit1,'Menubar','none',...
  'Units','normal','Position',[120/Scx 20/Scy 440/Scx 350/Scy]);
  set(0,'currentfig',Fig17);

% design menu
  pt_menu
  uimenu(Han_fil,'Label','Close','Sep','on','Callback',...
  'close(Fig17);clear Fig17');
end
	
w_range=logspace(w_start,w_end,pt);
delete(gca);
ngrid('new')
if (id>5)&((id~=10)|(id~=12))
  Amod=Amod*0;
  Amod(1)=1;
  id=1;
end
config;

if t_delay == 0
   [mmm,ddd] = bode(num,den,w_range); 
else
   if cloop == 1
       n0 = size(H_den);
      if n0(2) == 1, 
         cmpc = num(1)/den(1)*ones(size(w_range'));
      else
         [mmm,ddd] = nyquist(H_num,H_den,w_range);
         cmpc = mmm + sqrt(-1) * ddd;
      end
   end
   [mmm,ddd] = timdly(cloop,num,den,w_range,t_delay,cmpc);
end
mmm = 20 * log10(mmm);
if id > 9
   if t_delay == 0
      [mmmx,dddx] = bode(numx,denx,w_range);
   else
      [mmmx,dddx] = timdly(cloop,numx,denx,w_range,t_delay,cmpc);
   end
   mmmx = 20 * log10(mmmx);
   mmm = [mmm mmmx]; ddd = [ddd dddx];
   clear mmmx dddx
end
plot(ddd,mmm)
if id <= 9
   title('Nichols Plot')
else
   title('Nichols Plot - Yellow: Compensated')
end
grid
xlabel('Phase (degrees)')
ylabel('Magnitute dB')