function [GRADES] = grade_generator(n, mood, fail, accuracy)
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here
%
% Variables used:
% n: number of students
% mood: [1 or 2] 
% fail: failing rate (0 1)
% accuracy: Enter the desired accuracy of grades [0.5 0.25 0.1]

if n>1000 | n<0
    disp('****          *** You can impossibly teach so many students. n is set to 100.');
    disp('****')
    n = 100;
end

if mood>2 | mood<1
disp('****          *** Your mood does not exist. I assume you have a sunny day.');
disp('****')
mood=1;
end 

if fail>1 | fail<0
disp('****          *** Focus! You cannot have a rate which is larger than one or smaller than zero! Fail is set to 0.25');
disp('****')    
   fail=0.25;
end

skewlarge   = 1.7;  % skewness parameter
skewsmall   = 1.3;  % skewness parameter

n       =   round(n);
nfail   =   round(fail*n);
npass   =   n-nfail;

GRADES  =   zeros(n,1);

%%%%%%%%%%%%%%%%%%%%
%%%%  mood = 1  %%%%
%%%%%%%%%%%%%%%%%%%%
    if mood==1 %%%%%%%% good mood
        for i=1:npass % passing part
                if accuracy==0.5
                    GRADES(i,1)=abs(randn)*skewlarge+3.751;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.25
                    GRADES(i,1)=abs(randn)*skewlarge+3.8751;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.1
                    GRADES(i,1)=abs(randn)*skewlarge+3.951;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if GRADES(i,1)>6
                    GRADES(i,1)=6;
                end
                if GRADES(i,1)<4
                    GRADES(i,1)=4;
                end
        end
        for i=npass+1:n %failing part
                if accuracy==0.5
                    GRADES(i,1)=-abs(randn)/skewsmall+3.74999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.25
                    GRADES(i,1)=-abs(randn)/skewsmall+3.874999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.1
                    GRADES(i,1)=-abs(randn)/skewsmall+3.94999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if GRADES(i,1)<1
                    GRADES(i,1)=1;
                end
        end
    end
    %%%%%%%%%%%%%%%%%%%%
    %%%%  mood = 2  %%%%
    %%%%%%%%%%%%%%%%%%%%
    if mood==2 % bad mood
        for i=1:npass % passing part
                if accuracy==0.5
                    GRADES(i,1)=abs(randn)/skewsmall+3.751;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.25
                    GRADES(i,1)=abs(randn)/skewsmall+3.8751;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.1
                    GRADES(i,1)=abs(randn)/skewsmall+3.951;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if GRADES(i,1)>6
                    GRADES(i,1)=6;
                end
                if GRADES(i,1)<4
                    GRADES(i,1)=4;
                end
        end
        for i=npass+1:n %failing part
                if accuracy==0.5
                    GRADES(i,1)=-abs(randn)*skewsmall+3.74999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.25
                    GRADES(i,1)=-abs(randn)*skewsmall+3.874999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if accuracy==0.1
                    GRADES(i,1)=-abs(randn)*skewsmall+3.94999;
                    GRADES(i,1)=round(GRADES(i,1)/accuracy)*accuracy;
                end
                if GRADES(i,1)<1
                    GRADES(i,1)=1;
                end
        end
    end


Mean_grade  = sum(GRADES)/n; % somehow, the mean() command won't work here
Failingrate = round(nfail/n/0.01)*0.01;

disp('****')
disp('****    HEUREKA! Your grades:')
disp('****')
disp('Mean:')
disp(Mean_grade)
disp('Failing rate:')
disp(Failingrate)

x=(1:accuracy:6);
histo=hist(GRADES,x);
scrsz = get(0,'ScreenSize');
f=figure('Position',[scrsz(3)*0.47 scrsz(4)*0.1 scrsz(3)/2 scrsz(4)/2],'Name','Histogram');
hist(GRADES,x)
axis([1-accuracy/2 6+accuracy/2 0 max(histo)]);
xlabel('Grade');
ylabel('Density');
title1=title('Distribution of Grades');
set(title1,'FontWeight','bold') 
saveas(f,'histogram.fig')
saveas(f,'histogram.jpg')

end