function pvldemo(action)
%PVLDEMO Padé via Lanczos (PVL) Demostration
                                                                
%   Zhaojun Bai
%   Professor of Computer Science and Mathematics 
%   3005 Kemper Hall 
%   Department of Computer Science 
%   University of California 
%   One Shields Avenue 
%   Davis, CA 95616
%
%   Phone: (530) 752-4874 
%   Fax:   (530) 752-4767 
%   email: bai@cs.ucdavis.edu
%
%   $Revision: 1.10 $  $Date: 2004/03/19 18:30:30 $

if nargin<1,
    action='initialize';
end;

% Problem Dependent Parameters
bf_awebook = 'AWEBOOK is taken from ..., ... is shown in the above axes, ... and ... ';
ep_awebook = 'Expansion Point: pi*1e9';
or_awebook = ' Order 4| Order 5| Order 6';
mat_awebook = str2mat('4','5','6');

bf_brake834 = 'BRAKE384 is taken from ..., ... is shown in the above axes, ... and ... ';
ep_brake834 = 'Expansion Point: 0';
or_brake834 = ' Order 39| Order 40| Order 41';
mat_brake834 = str2mat('39','40','41');

bf_peec = 'PEEC is taken from ..., ... is shown in the above axes, ... and ... ';
ep_peec = 'Expansion Point: 2*pi*1e9';
or_peec = ' Order 50| Order 55| Order 60| Order 65 | Order 70';
mat_peec = str2mat('50','55','60','65','70');

if strcmp(action,'initialize'),
    oldFigNumber=watchon;
    
    figNumber=figure( ...
        'Visible','off', ...
        'NumberTitle','off', ...
        'MenuBar', 'none', ...
        'Name','Padé via Lanczos (PVL) Demo');

    pos=get(figNumber,'Position');
    width=pos(3)-pos(1);
    pos(1)=pos(1)-width*0.5;
    pos(3)=pos(3)+width*0.5;
    set(figNumber,'Position',pos);
    
    %===================================
    % Set up the axes
    left=0.09;
    bottom=0.10;
    width=0.60;
    height=0.38;
    axRel=axes( ...
        'Units','normalized', ...
        'Position',[left bottom width height]);
    
    axMag=axes( ...
        'Units','normalized', ...
        'Position',[left 2*bottom+height width height]);

    %====================================
    % Information for all buttons
    labelColor=[0.8 0.8 0.8];
    top=0.95;
    bottom=0.05;
    left=0.75;
    yInitLabelPos=0.90;
    left=0.75;
    labelWid=0.20;
    labelHt=0.05;
    btnWid=0.20;
    btnHt=0.05;
    % Spacing between the label and the button for the same command
    btnOffset=0.003;
    % Spacing between the button and the next command's label
    spacing=0.05;

    %====================================
    % The CONSOLE frame
    frmBorder=0.02;
    yPos=0.05-frmBorder;
    frmPos=[left-frmBorder yPos btnWid+2*frmBorder 0.9+2*frmBorder];
    uicontrol( ...
        'Style','frame', ...
        'Units','normalized', ...
        'Position',frmPos, ...
        'BackgroundColor',[0.50 0.50 0.50]);
    
    %====================================
    % The EXAMPLE popup button
    btnNumber=1;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelStr='Example';
    labelList=' awebook| brake834| peec';
    cmdList=str2mat( ...
        'awebook','brake834','peec');
    callbackStr='pvldemo(''reset'')';
    
    % Generic label information
    labelPos=[left yLabelPos-labelHt labelWid labelHt];
    uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    % Generic popup button information
    btnPos=[left yLabelPos-labelHt-btnHt-btnOffset btnWid btnHt];
    hndlEx=uicontrol( ...
        'Style','popup', ...
        'Units','normalized', ...
        'Position',btnPos, ...
        'String',labelList, ...
        'Callback',callbackStr, ...
        'UserData',cmdList);

    %====================================
    % The ORDER popup button
    btnNumber=2;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelStr='Padé approximation';
    labelList=or_awebook;
    cmdList=mat_awebook;
    callbackStr='pvldemo(''eval'')';
    
    % Generic label information
    labelPos=[left yLabelPos-labelHt labelWid labelHt];
    uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    % Generic popup button information
    btnPos=[left yLabelPos-labelHt-btnHt-btnOffset btnWid btnHt];
    hndlOr=uicontrol( ...
        'Style','popup', ...
        'Units','normalized', ...
        'Position',btnPos, ...
        'String',labelList, ...
        'Callback',callbackStr, ...
        'UserData',cmdList);

    %====================================
    % The EXPANSION POINT text field
    btnNumber=3;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelStr=ep_awebook;
    
    % Generic label information
    labelPos=[left yLabelPos-labelHt labelWid labelHt];
    hndlEp=uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    %====================================
    % The static text field
    btnNumber=4;
    yLabelPos=top-(btnNumber-1)*(btnHt+labelHt+spacing);
    labelColor=[0.94 0.94 0.94];
    labelStr=bf_awebook;
    
    % Generic label information
    labelPos=[left yLabelPos-labelHt-2*btnHt labelWid labelHt+3*btnHt];
    hndlBf=uicontrol( ...
        'Style','text', ...
        'Units','normalized', ...
        'Position',labelPos, ...
        'BackgroundColor',labelColor, ...
        'HorizontalAlignment','left', ...
        'String',labelStr);

    %====================================
    % The info button
    uicontrol( ...
        'Style','pushbutton', ...
        'Units','normalized', ...
        'Position',[left bottom+2*btnHt+spacing btnWid 2*btnHt], ...
        'String','Info', ...
        'Callback','pvldemo(''info'')');

    % The close button.
    uicontrol( ...
        'Style','pushbutton', ...
        'Units','normalized', ...
        'Position',[left bottom btnWid 2*btnHt], ...
        'String','Close', ...
        'Callback','close(gcf)');

    % Uncover the figure
    hndlList=[axRel axMag hndlEx hndlOr hndlEp hndlBf];
    watchoff(oldFigNumber);
    set(figNumber,'Visible','on', ...
        'UserData',hndlList);
    pvldemo('eval');

elseif strcmp(action,'info'),
    helpwin(mfilename)
    
elseif strcmp(action,'reset'),
    hndlList=get(gcf,'UserData');
    hndlEx = hndlList(3);
    hndlOr = hndlList(4);
    hndlEp = hndlList(5);
    hndlBf = hndlList(6);
    StrList = get(hndlEx, 'UserData');
    StrVal = get(hndlEx, 'Value');
    Str = deblank(StrList(StrVal,:));
    if strcmp(Str, 'awebook'),
        set(hndlOr, 'String', or_awebook, 'UserData', mat_awebook);
        set(hndlEp, 'String', ep_awebook);
        set(hndlBf, 'String', bf_awebook);
    elseif strcmp(Str, 'brake834'),
        set(hndlOr, 'String', or_brake834, 'UserData', mat_brake834);
        set(hndlEp, 'String', ep_brake834);
        set(hndlBf, 'String', bf_brake834);
    elseif strcmp(Str, 'peec'),
        set(hndlOr, 'String', or_peec, 'UserData', mat_peec);
        set(hndlEp, 'String', ep_peec);
        set(hndlBf, 'String', bf_peec);
    end
    pvldemo('eval');

elseif strcmp(action,'eval'),
    % Assemble and execute the completed command 
    hndlList=get(gcf,'UserData');
    
    % order of reduced model 
    hndlOr = hndlList(4);
    StrList = get(hndlOr, 'UserData');
    StrVal = get(hndlOr, 'Value');
    Str = deblank(StrList(StrVal,:));
    n = str2num(Str);

    hndlEx = hndlList(3);
    StrList = get(hndlEx, 'UserData');
    StrVal = get(hndlEx, 'Value');
    Str = deblank(StrList(StrVal,:));
    if strcmp(Str, 'awebook'),
        %====================================
        % AWEBOOK

        % read in data
        awebookeg; 
        N = size(C,1); 

        % expansion point 
        s0 = 1*pi*1e+9;

        % Reduced-order modeling 
        [Cn,Gn,bn,ln] = romlin(N,C,G,b,l,n,s0); 

        % Bode plot 
        npts = 1001;
        freqlow = 10^0;
        freqhig = 2*10^(10);
        linst = (freqhig-freqlow)/(npts-1);
        freq = freqlow:linst:freqhig;
        s = 2*pi*sqrt(-1)*freq;
        freqpts = max(size(s));

        for k = 1:freqpts,
            Hn(k) = ln'*((Gn + s(k)*Cn)\bn); 
        end

        % Transfer function - exact 
        for k = 1:freqpts,
            HN(k) = l'*((G+s(k)*C)\b);
        end

        % Transfer function - approximation 
        for k = 1:freqpts,
            Hn(k) = ln'*((Gn + s(k)*Cn)\bn);
        end

        axMag = hndlList(2);
        axes(axMag);
        plot(abs(freq),20*log10(abs(HN)),'r-', abs(freq),20*log10(abs(Hn)),'b--');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('Gain (dB)', 'fontsize', 12);
        legend('Exact', 'PVL');
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);

        axRel = hndlList(1);
        axes(axRel);
        plot(abs(freq),angle(HN)*180/pi,'r-', abs(freq),angle(Hn)*180/pi,'b--');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('phase(degree)', 'fontsize', 12);
        legend('Exact', 'PVL');
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);
    elseif strcmp(Str, 'brake834'),
        % load matrix data, and exact values of transfer function
        load brake834M; 
        load brake834K; 
        C = M;
        G = K;
        N = size(C,1); 
        l = zeros(N,1);
        l(1)=1; 
        b = l;

        % expansion point 
        s0 = 0;

        % Reduced-order modeling 
        [Cn,Gn,bn,ln] = romlin(N,C,G,b,l,n,s0);

        % Bode plot 
        npts = 501;
        freqlow = 0;
        freqhig = 10000;
        freq = linspace(freqlow,freqhig,npts);
        s = 2*pi*sqrt(-1)*freq;
        freqpts = max(size(s));

        % evaluate the transfer function of the reduced-order model 
        for k = 1:freqpts,
            Hn(k) = ln'*((Gn+s(k)^2*Cn)\bn);
        end

        % ``exact'' transfer function 
        %for k = 1:freqpts,
        %    HN(k) = l'*((G+s(k)^2*C)\b);
        %end
        % precalculated
        load brake834freqexact; 

        axMag = hndlList(2);
        axes(axMag);
        semilogy(abs(freq),abs(HN),'r-', abs(freq),abs(Hn),'b--');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('Magnitude', 'fontsize', 12);
        legend('Exact', 'PVL');
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);

        axRel = hndlList(1);
        axes(axRel);
        semilogy(abs(freq),abs(HN-Hn)./abs(HN),'b-');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('Relative error', 'fontsize', 12);
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);
    elseif strcmp(Str, 'peec'),
        % load data
        load ex306v4;   % matrix data, and exact values of transfer function
        C = CM;
        G = GM;
        l = LM(:,1);
        b = LM(:,2);
        N=size(C,1); 

        % expansion point 
        s0 = 2*pi*1e+9;

        % reduced-order modeling
        [Ck,Gk,bk,lk]=romlin(N,C,G,b,l,n,s0); 

        % Bode plot
        npts = 1001;
        freqlow = 10^0;
        freqhig = 0.5*10^(10);
        % linear space
        linst = (freqhig-freqlow)/(npts-1);
        freq = freqlow:linst:freqhig;
        s = 2*pi*sqrt(-1)*freq;
        freqpts = max(size(s));

        % ``exact'' transfer function
        % tic;
        % for k = 1:freqpts,
        %     HN(k) = l'*((G+s(k)*C)\b);
        % end
        % Fullmodel_cputime=toc
        % precalculated
        load ex306v4HN;

        % transfer function of reduced-order model 
        tic; 
        for k = 1:freqpts,
            Hn(k) = lk'*((Gk+s(k)*Ck)\bk);
        end
        Reducedordermodel_cputime = toc;

        % This is not exactly bode polt, but commonly as presented in literature
        axMag = hndlList(2);
        axes(axMag);
        plot(abs(freq),abs(HN),'r-', abs(freq),abs(Hn),'b--');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('Voltage (Volts)', 'fontsize', 12);
        legend('Exact', 'PVL');
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);

        axRel = hndlList(1);
        axes(axRel);
        semilogy(abs(freq),abs(HN-Hn)./abs(HN),'b-');
        xlabel('Frequency (Hz)', 'fontsize', 12);
        ylabel('Relative error', 'fontsize', 12);
        %set(gca, 'fontsize', 12, 'linewidth', 1.5);
    end
    
end;    % if strcmp(action, ...