how i can fix this axes error ?

Hi

i have popup menu and two axes, one axes show image and another one two show plot, when i write number in edit text than press push button show plot in axes and i have more than one plot but found error when i select next one my code is :

val = get(handles.popup,'Value'); %get currently selected option from menu
str = get(handles.popup,'string'); 

if val==1

          axes(handles.plotaxes);
          a = str2num(get(handles.edit1,'String'));
          b = str2num(get(handles.edit2,'String'));
          n1=length (a)
          n2=length (b)
          x=0:1:n1-1;
          subplot (2, 2, 1), stem(x, a); 
          title ('INPUT SEQUENCE1'); 
          xlabel ('---->n');
          ylabel ('---->a (n)');
          y=0:1:n2-1;
          subplot (2, 2, 2), stem(y, b); 
          title ('INPUT SEQUENCE2'); 
          xlabel ('---->n');
          ylabel('---->b(n)'); 
          c=conv (a, b); 
          n3=0:1:n1+n2-2;
          subplot (2, 1, 2), stem (n3, c);
          title ('CONVOLUTION OF TWO SEQUENCES');
          xlabel ('---->n');
          ylabel ('---->c (n)')
  elseif val==2
          a = str2num(get(handles.edit1,'String'));
          b = str2num(get(handles.edit2,'String'));
          n1=length (a);
          n2=length (b);
          n3=n1-n2;
          N=max (n1, n2);
          if (n3>0);
              b= b, zeros (1, n1-n2);
              n2=length (b);
          else
              a= a, zeros (1, N-n1);
              n1=length (a);
          end
          k=max (n1, n2);
          a=a'; b=b'; c=b;
          for i=1: k-1 
              b=circshift (b, 1);
              c=[c, b];
          end;
          disp(c);
          z=c*a; 
          disp ('z=') 
          disp (z)
          subplot (2, 2, 1);
          stem (a,'filled');
          title ('INPUT SEQUENCE1');
          xlabel ('---->n');
          ylabel ('---->Amplitude');
          subplot (2, 2, 2);
          stem (b,'filled');
          title ('INPUT SEQUENCE2');
          xlabel ('---->n');
          ylabel ('---->Amplitude');
          subplot (2, 1, 2);
          stem (z,'filled');
          title ('CONVOLUTION OF TWO SEQUENCES');
          xlabel ('---->n');
          ylabel ('---->Amplitude');
  end;

this is the error:

Error using axes
Invalid object handle

Error in dspgui>plotbutton_Callback (line 201)
        axes(handles.plotaxes);

Error in gui_mainfcn (line 96)
        feval(varargin{:});

Error in dspgui (line 42)
    gui_mainfcn(gui_State, varargin{:});

Error in @(hObject,eventdata)dspgui('plotbutton_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating uicontrol Callback

Answer 1

[David Sanchez]

You are not declaring

axes(handles.plotaxes);

after

if val==2

Answer 2

[Walter Roberson]

subplot() deletes any existing axes that the subplot would cover. So your subplot(2,2,1) deletes the existing axis handles.plotaxes

subplot() applies to figure (or uipanels), not to axes. I don't think you can have axes objects that are children of other axes objects (but maybe it is possible through hggroup, I would have to research.)