How do I debug this program?

This enclosed BMI program does not work correctly for all parameters. For example, a person that is 6'2" tall and weighs 194 lbs the calculated BMI is 24.9, but the program shows the weight status as "obese". I need to debug this program, but don't understand what the bug is or how to fix it.

function varargout = BMI(varargin)
% BMI MATLAB code for BMI.fig
%      BMI, by itself, creates a new BMI or raises the existing
%      singleton*.
%
%      H = BMI returns the handle to a new BMI or the handle to
%      the existing singleton*.
%
%      BMI('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in BMI.M with the given input arguments.
%
%      BMI('Property','Value',...) creates a new BMI or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before BMI_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to BMI_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help BMI

% Last Modified by GUIDE v2.5 15-Nov-2012 21:11:46

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @BMI_OpeningFcn, ...
                   'gui_OutputFcn',  @BMI_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT

% --- Executes just before BMI is made visible.
function BMI_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to BMI (see VARARGIN)

% Choose default command line output for BMI
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes BMI wait for user response (see UIRESUME)
% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.
function varargout = BMI_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;

function feet_Callback(hObject, eventdata, handles)
% hObject    handle to feet (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of feet as text
%        str2double(get(hObject,'String')) returns contents of feet as a double

% --- Executes during object creation, after setting all properties.
function feet_CreateFcn(hObject, eventdata, handles)
% hObject    handle to feet (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function inch_Callback(hObject, eventdata, handles)
% hObject    handle to inch (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of inch as text
%        str2double(get(hObject,'String')) returns contents of inch as a double

% --- Executes during object creation, after setting all properties.
function inch_CreateFcn(hObject, eventdata, handles)
% hObject    handle to inch (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

function weight_Callback(hObject, eventdata, handles)
% hObject    handle to weight (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of weight as text
%        str2double(get(hObject,'String')) returns contents of weight as a double

% --- Executes during object creation, after setting all properties.
function weight_CreateFcn(hObject, eventdata, handles)
% hObject    handle to weight (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
feet = str2num(get(handles.feet, 'string'));
inch = str2num(get(handles.inch, 'string'));
weight = str2num(get(handles.weight, 'string'));

bmi = weight*703/(feet*12+inch)^2;
set(handles.BMI, 'string', sprintf('%.1f',bmi));

if bmi<18.5
    set(handles.status, 'string', 'Underweigth');
elseif bmi <= 24.9 && bmi>=19
    set(handles.status, 'string', 'Normal');
elseif bmi > 25 && bmi <=29.9
    set(handles.status, 'string', 'Overweight');
else
    set(handles.status, 'string', 'Obese');
end

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Note that with your structure of if/elseif you do not need to test for the lower part of each range:

if bmi < 18.5
elseif bmi <= 25
elseif bmi < 30
else
end

Notice I did not use 24.9 or 29.9 as you were missing out on all values greater than 24.9 and less than 25. MATLAB does not calculate to only single digits, remember.