%-----------------------------------------------------------------------------%
% GRADES PROCESSING EXAMPLE                                                   %
% 10/21/2001 DIS                                                              %
%-----------------------------------------------------------------------------%
% Initialize data:                                                            %
  clc, clear                       % clean things up                          %
  highGrade  = 100;                % highest possible grade                   %
  lowGrade   = 0;                  % lowest possible grade                    %
  maxGrade   = lowGrade;           % the max grade so far                     %
  minGrade   = highGrade;          % the min grade so far                     %
  sumGrade   = 0;                  % sum of grades entered so far             %
  countGrade = 0;                  % count of VALID grades so far             %
  allGrades  = [];                 % collection of grades so far              %
%-----------------------------------------------------------------------------%
% Welcome the user:
  disp('+---------------------------------------------------------+');
  disp('| Welcome to the grades processing program!               |');
  disp('| You will be prompted to enter grades.                   |');
  disp('| Be sure to enter real, finite numbers.                  |');
  disp('| Enter a value less than 0 or greater than 100 to quit.  |');  
  disp('+---------------------------------------------------------+');
%-----------------------------------------------------------------------------%
% Prompt for first grade. The user must enter a real, finite number. 
% Reprompt the user otherwise:                             
  grade = str2double(input('  Enter a grade: ','s'));
  while ~isreal(grade) | isinf(grade) | isnan(grade) | ~isnumeric(grade)
    disp('  Please enter a real, finite number: ');
    grade = str2double(input('  Enter a grade: ','s'));
  end
%-----------------------------------------------------------------------------%
% Process grades:
% - store the grades
% - find the sum and count
% - determine the max/min grades
% Stop processing when the user enters an out-of-bounds grade:
  while grade >= lowGrade & grade <= highGrade

    % Increment count of valid grades:
      countGrade = countGrade + 1;

    % Accumulate sum of valid grades:
      sumGrade = sumGrade + grade;
      
    % Store the current grade:
      allGrades(countGrade) = grade;
      
    % Update the max grade so far, if necessary:
      if grade > maxGrade 
	maxGrade = grade;
      end

    % Update the min grade so far, if necessary:
      if grade < minGrade 
	minGrade = grade;
      end
      
    % Get next grade:
      grade = str2double(input('  Enter a grade: ','s'));
      while ~isreal(grade) | isinf(grade) | isnan(grade) | ~isnumeric(grade)
	disp('  Please enter a real, finite number: ');
	grade = str2double(input('  Enter a grade: ','s'));
      end
  
  end % continue processing grades
%-----------------------------------------------------------------------------%
% Report the number of valid grades entered:
  disp('+---------------------------------------------------------+');
  disp('| Done processing grades!                                 |');
  disp('+---------------------------------------------------------+');
  if countGrade==0
    disp('| No valid grades entered!                                |');
    disp('+---------------------------------------------------------+');
  else
    disp(['  Amount of grades entered: ',num2str(countGrade)]);
    disp(['  Maximum grade entered:    ',num2str(maxGrade)]);
    disp(['  Minimum grade entered:    ',num2str(minGrade)]);
    disp(['  Average of all grades:    ',num2str(sumGrade/countGrade)]);
    disp(['  Collection of grades:']);
    for ii=1:countGrade
      disp(['    Count: ',num2str(ii),', Grade: ',num2str(allGrades(ii))]);
    end    
    disp('+---------------------------------------------------------+');
  end
%-----------------------------------------------------------------------------%
% Future additions:
% - round average
% - other statistical data
% - plot grades with hist(allGrades)
% - prompt user to enter Y or N to continue program
%   choice = input(.....), while choice...., reprompt, end
% - store grade info in file
%-----------------------------------------------------------------------------%