title: Incorrect subtraction value in Matlab GUI
body: <p>I am working with COM port and I am getting a value (e.g. temperature value) from COM. Now when I am trying to subtract a specific value (e.g. 8) from this value it is not showing desired value. Here is the code:</p>
  
  <pre><code>function pushbutton1_Callback(hObject, eventdata, handles)
    instrreset; %resets the serial devices
    clc;
    s = serial ('COM6');
    RxText3 = fscanf(handles.serConn);
    key = 8;
    P = minus(RxText3,key);
    set(handles.tempserial,'string',P);
    fclose(s);
  </code></pre>
  
  <p>What I am expecting:
  Suppose I am getting a value as 32 and my key value is 8. Then I am expecting to get 24.</p>
  
  <p>What I am getting:
  I am getting two values as 42 and 45.</p>
  
  <p>Additional problem:</p>
  
  <p>How can I set the value so that it would show 24 Celcius? I tried this : set(handles.tempserial,'string',P, 'Celcius') in which case nothing is shown.</p>