function Grade = Curve(score)
% function Grade=Curve(score)
% Determines the letter grade given a % score based on a 10%/grade 
% Based on Palm problem 4-17
% Input:  score = students score (%)
% output: Grade = letter grade (A, B, C, D or F)
% S. Scott Moor             March 2008

% if structure is used to select a grade 
% initial if performs error trapping 
if score >100 || score < 0
    disp('ERROR: Input Score must be between 0 and 100')
    Grade = NaN;
elseif score >= 90
   Grade = 'A';
elseif score >= 80 
   Grade = 'B';
elseif score >= 70 
   Grade = 'C';
elseif score >=60 
   Grade = 'D';
else
   Grade = 'F';
end