function MTFgraph(maxfreq, age, p)
%MTFgraph(maxfreq, age, p) Graphs a series of MTF functions in order to compare
%them
%

if (nargin > 1)  
	q = [0:1:maxfreq-1];
	mtf = [0:1:maxfreq-1];
	m = pigment;
	for i = 1:length(q)
		mtf(i) = MTFip(q(i), p, age, m);
	end
	plot(q, mtf)
else
	numsubs = input('How many subjects would you like to compare (up to 4)');
	for n = 1:numsubs
		switch n
			case{1}
				q1 = [0:1:maxfreq-1];
				mtf1 = [0:1:maxfreq-1];
				age1 = input('What is the age of the first subject?');
				p1 = input('What is the pupil diameter (in mm)?');
				m1 = pigment;
				for i = 1:length(q1)
					mtf1(i) = MTFip(q1(i), p1, age1, m1);
				end
			case{2}
				q2 = [0:1:maxfreq-1];
				mtf2 = [0:1:maxfreq-1];
				age2 = input('What is the age of the second subject?');
				p2 = input('What is their pupil diameter (in mm)?');
				m2 = pigment;
				for i = 1:length(q2)
					mtf2(i) = MTFip(q2(i), p2, age2, m2);
				end
			case{3}
				q3 = [0:1:maxfreq-1];
				mtf3 = [0:1:maxfreq-1];
				age3= input('What is the age of the third subject?');
				p3 = input('What is their pupil diameter (in mm)?');
				m3 = pigment;
				for i = 1:length(q3)
					mtf3(i) = MTFip(q3(i), p3, age3, m3);
				end
			case{4}
				q4 = [0:1:maxfreq-1];
				mtf4 = [0:1:maxfreq-1];
				age4 = input('What is the age of the fourth subject?');
				p4 = input('What is their pupil diameter (in mm)?');
				m4 = pigment;
				for i = 1:length(q4)
					mtf4(i) = MTFip(q4(i), p4, age4, m4);				
				end
		end
	end
	
	switch numsubs
		case{1}
			plot(q1, mtf1)
			legend('Subject1')
		case{2}
			plot(q1,mtf1,q2,mtf2)
			legend('Subject1','Subject 2')
		case{3}
			plot(q1,mtf1,q2,mtf2,q3,mtf3)
			legend('Subject1', 'Subject2', 'Subject3')
		case{4}
			plot(q1,mtf1,q2,mtf2,q3,mtf3,q4,mtf4)
			legend('Subject1', 'Subject2', 'Subject3', 'Subject4')
	end		


end	

xlabel('spatial frequency(cpd)')
ylabel('modulation transfer')
title('Modulation Transfer Functions with varying age, pigmention, and pupil size')