---

function pushbutton1_Callback(hObject, eventdata, handles)

f_str = get(handles.edit1, 'String');
a = str2double(get(handles.edit2, 'String'));
b = str2double(get(handles.edit3, 'String'));

f = @(x) eval(vectorize(f_str));

x = linspace(a, b, 1000);
y = f(x);

axes(handles.axes1);
plot(x, y);
grid on;
xlabel('x');
ylabel('f(x)');
title('График функции');