程式三部曲－－絕地大反攻！

利用上兩節所敘述之增添與修正，最後的程式應為如下之型式與內容：

  function simple_gui
  % SIMPLE_GUI Select a data set from the pop-up menu, then
  % click one of the plot-type push buttons. Clicking the button
  % plots the selected data in the axes.

     %  Create and then hide the GUI as it is being constructed.
     f = figure('Visible','off','Position',[360,500,450,285]);

     %  Construct the components.
     hsurf = uicontrol('Style','pushbutton','String','Surf',...
            'Position',[315,220,70,25],...
            'Callback',{@surfbutton_Callback});
     hmesh = uicontrol('Style','pushbutton','String','Mesh',...
            'Position',[315,180,70,25],...
            'Callback',{@meshbutton_Callback});
     hcontour = uicontrol('Style','pushbutton',...
            'String','Countour',...
            'Position',[315,135,70,25],...
            'Callback',{@contourbutton_Callback});
     htext = uicontrol('Style','text','String','Select Data',...
            'Position',[325,90,60,15]);
     hpopup = uicontrol('Style','popupmenu',...
            'String',{'Peaks','Membrane','Sinc'},...
            'Position',[300,50,100,25],...
            'Callback',{@popup_menu_Callback});
     ha = axes('Units','Pixels','Position',[50,60,200,185]);
     align([hsurf,hmesh,hcontour,htext,hpopup],'Center','None');
 
     % Create the data to plot.
     peaks_data = peaks(35);
     membrane_data = membrane;
     [x,y] = meshgrid(-8:.5:8);
     r = sqrt(x.^2+y.^2) + eps;
     sinc_data = sin(r)./r;
 
     % Initialize the GUI.
     % Change units to normalized so components resize
     % automatically.
     set([f,ha,hsurf,hmesh,hcontour,htext,hpopup],'Units','normalized');
     %Create a first plot in the axes.
     current_data = peaks_data;
     surf(current_data);
     % Assign the GUI a name to appear in the window title.
     set(f,'Name','Simple GUI')
     % Move the GUI to the center of the screen.
     movegui(f,'center')
     % Make the GUI visible.
     set(f,'Visible','on');

     %  Callbacks for simple_gui. These callbacks automatically
     %  have access to component handles and initialized data
     %  because they are nested at a lower level.

     %  Pop-up menu callback. Read the pop-up menu Value property
     %  to determine which item is currently displayed and make it
     %  the current data.
        function popup_menu_Callback(source,eventdata)
           % Determine the selected data set.
           str = get(source, 'String');
           val = get(source,'Value');
           % Set current data to the selected data set.
           switch str{val};
           case 'Peaks' % User selects Peaks.
              current_data = peaks_data;
           case 'Membrane' % User selects Membrane.
              current_data = membrane_data;
           case 'Sinc' % User selects Sinc.
              current_data = sinc_data;
           end
        end

     % Push button callbacks. Each callback plots current_data in
     % the specified plot type.

     function surfbutton_Callback(source,eventdata)
     % Display surf plot of the currently selected data.
        surf(current_data);
     end

     function meshbutton_Callback(source,eventdata)
     % Display mesh plot of the currently selected data.
        mesh(current_data);
     end

     function contourbutton_Callback(source,eventdata)
     % Display contour plot of the currently selected data.
        contour(current_data);
     end

  end

其執行之結果應與前面使用Guide所做的相同，讀者不妨一試，並比較其差異性。到底兩種方法之優劣如何呢？你能設法像本方法一樣，拷貝前一方法所討論的程式而加以執行嗎？