The simplest is to store your feature vector in handles.
% --- Executes on button press in pushbutton4.
function pushbutton4_Callback(hObject, eventdata, handles)
handles.featureVector = extractHOGFeatures(Img); %store feature vector in handles
guidata(hObject, handles); %and save handles
end
function pushbutton5_Callback(hObject, eventdata, handles)
Classifier=trainedClassifier;
Label=Classifier.predictFcn(handles.featureVector); %get feature vector from handles
...
end
