%FBLKB Frequency-domain block-build (MIMO).
%
% A script file which assembles subsystem MVFR files named
% F1,F2,...,Fn into a single file named F, for use with function FCON.
% It also creates the matrix sz needed by FCON.
%
% Before calling FBLKB the following variables must exist:
%      w = the frequency vector
%  fblks = a vector of integers. If fblks(i)==x then the i'th 
%          subsystem's frequency response should be in 'FX', where 
%          X = int2str(x). If fblks is a single integer n, it is expanded 
%          to the vector 1:n.
%   {FX} = set of MVFR matrices containing frequency responses of 
%          subsystems. Only those FX's identified in fblks are used, and
%          they are assembled into F in the order in which they appear
%          in fblks.
%
%  If the variable verbose == 1 then fblkb reports what it finds.
%
%  Existing variables sz and F are overwritten.

% Copyright (C) 1989 by Cambridge Control Ltd
% J.M.Maciejowski, 8 March 1989. Revised 5 May 1989.

f_trace = 0;
if exist('verbose')
  if verbose == 1
    f_trace = 1;
    disp('FBLKB')
  end
end

% Find frequency list w:
if ~exist('w'),
  disp(' ERROR: Frequency list w does not exist')
  clear f_trace;
  return
end

% Find fblks and expand if necessary:
if exist('fblks')
  if length(fblks)==1,
    f_nblk = 1:fblks;  % Expand
  else 
    f_nblk = fblks(:)';  % Make sure it's a row vector
  end
  if isempty(f_nblk),
    if f_trace,
      disp('    No block numbers defined')
    end
    clear f_trace f_nblk;
    return
  elseif f_trace
    disp('    Frequency response block numbers are (fblks) :')
    disp(f_nblk)
  end
else
  disp(' ERROR: Variable fblks does not exist')
  clear f_trace f_nblk;
  return
end

% Define values of yes and no for user input:
yes = 1;  no = 0;

f_yesno = no;
if exist('sz'),
  if f_trace,
    disp('    WARNING: Pre-existing variable sz will be overwritten')
    f_yesno = input('            Shall I continue (yes/no) ? ');
    if f_yesno ~= yes,
      disp('*** ABORTING FBLKB to avoid overwriting sz')
      clear f_trace f_nblk yes no f_yesno;
      return
    end
  end
  sz=[];
end

f_yesno = no;
if exist('F'),
  if f_trace,
    disp('    WARNING: Pre-existing variable F will be overwritten')
    f_yesno = input('            Shall I continue (yes/no) ? ');
    if f_yesno ~= yes,
      disp('*** ABORTING FBLKB to avoid overwriting F')
      clear f_trace f_nblk yes no f_yesno;
      return
    end
  end
  F=[];
end

% Assemble frequency responses:
for f_block = 1 : length(f_nblk),
  f_num = f_nblk(f_block);
  f_name = ['F',int2str(f_num)];
  if ~exist(f_name),
    if f_trace,
      disp(['    WARNING: Cannot find block ',f_name])
      disp(['             Block ',f_name,' omitted from F'])
    end
  else   % Block exists
    [f_out,f_in] = fsize(w,eval(f_name));
    sz = [sz [f_in;f_out]];
    if f_trace,
      disp(['    Block ',f_name,' has ',int2str(f_in),' inputs and ',...
	     int2str(f_out),' outputs'])
    end
    F = [ F, fget(w,eval(f_name)) ];
  end
end

if f_trace,
  [f_szr,f_szc] = size(sz);
  disp(' ')
  disp(['    Number of blocks assembled in F : ',int2str(f_szc)])
end  

% Clear all internal variables introduced by fblkb:
clear f_trace;  % 1 if verbose==1, 0 otherwise
clear f_nblk;   % Block naming integers
clear yes no;   % == 1 ,  0.
clear f_yesno;  % User's response
clear f_block;  % Ordinal number of block being handled
clear f_num;    % Integer name of block being handled
clear f_name;   % Name of block (as string)
clear f_in;     % Number of inputs of block being handled
clear f_out;    % Number of outputs of block being handled
clear f_szr;    % Number of rows in sz
clear f_szc;    % Final number of columns in sz