function charex(a)
%charex takes a real number a as input and graphs sin(ax) over the interval
%[0, 2pi]. There is no output other than the graph.
x = linspace(0,2*pi);
y = sin(a*x);
plot(x,y)
xlabel('x')
ylabel('y')
title(['Graph of y = sin(',num2str(a),'x)'])
axis tight
end