GUI Push Button Undefined Variable

I am attempting to create a GUI with a push button that solves some equations for me. The data that it is using is gained from some edit text boxes. This is how the data is being read in:

function edit2_Callback(hObject, eventdata, handles)

r = str2double(get(handles.edit2,'string'));
assignin('base','r',r)

In my workspace, the variable r shows up as the value that was inputted. In the push button callback I am attempting to access that variable and it shows up with an error of "Reference to non-existent field 'r'".

This is what my code for the push button looks like:

 function pushbutton1_Callback(hObject, eventdata, handles)

%%Find Chi
r1 = 2*handles.r+2;
r2 = 2*handles.r;

I have tried removing the handles from this expression as well and that gave me the same error.

Answer 1

[Geoff Hayes]

Sara - the handles structure does not reference those variables that you save to the workspace. It only includes the handles to the GUI controls and any user-defined data that you have saved to the structure using guidata. As such, you can access your edit2 control directly through the handles object. Remove the edit2_Callback function, and within the push button callback do

 function pushbutton1_Callback(hObject, eventdata, handles)

 r = str2double(char(get(handles.edit2,'String')));
 %%Find Chi
 r1 = 2*r+2;
 r2 = 2*r;

% etc.

Try the above and see what happens!

As an aside, in your edit2_Callback you do the following

 r = str2double(get(handles.edit2,'string'));

In this case, you don't need to access handles as hObject is handles.edit2.

[Sara Koniecko]

I have 3 edit text boxes that I need to do this for, can I use this method for all of them and just replace the tag that is associated with handles?

[Geoff Hayes]

Yes, Sara. Just do the same as above, using the tag of the control as a field within handles. For example,

 get(handles.edit1,'String');
 get(handles.edit2,'String');

etc.