MATLAB Creating Graphical User Interfaces

catch EM

% Cannot evaluate expression user typed

set(handles.plot_button,'String','Cannot plot t');

uicontrol(hObject);

end

The catch block changes the label on the Plot button to indicate that an input value was

invalid. The uicontrol command sets the focus to the field that contains the erroneous

value.

plot_button_Callback

The plot_button_Callback function executes when the user clicks the Plot button.

First, the callback gets the values in the three edit fields:

f1 = str2double(get(handles.f1_input,'String'));

f2 = str2double(get(handles.f2_input,'String'));

t = eval(get(handles.t_input,'String'));

Then callback uses values of f1, f2, and t to sample the function in the time domain and

calculate the Fourier transform. Then, the two plots are updated:

% Create frequency plot in proper axes

plot(handles.frequency_axes,f,m(1:257));

set(handles.frequency_axes,'XMinorTick','on');

grid(handles.frequency_axes,'on');

% Create time plot in proper axes

plot(handles.time_axes,t,x);

set(handles.time_axes,'XMinorTick','on');

grid on

See Also

Related Examples

• “Create a Simple App Using GUIDE” on page 2-2


• “Write Callbacks in GUIDE” on page 7-2


• “Share Data Among Callbacks” on page 11-2

8 Examples of GUIDE UIs