%Plot addition of two counterpropagating sin waves and sum.

clf();
xmax = 6*pi; %Change this value to see different standing waves
x=0:0.01:xmax;
ymax = 4;
k1=1;
k2=1;
waves= k1*xmax/(2*pi); %This calculates the number of displayed wavelengths.
w1=-1/(5*pi); %wave propagating to the left
w2= 1/(5*pi); %wave propagating to the right

for t = 1:100 % Change this for % of period to animate; 25 = 1/4 period, 50 = 1/2 etc.
    Ei = sin(k1*x-w1*t);
    Er = sin(k2*x-w2*t);
    Esum = Ei+Er;
    plot(x, Ei, x, Er, x, Esum);
    xlim([0, xmax]);
    ylim([-ymax, ymax]);
    title(['Standing EM Wave for ' num2str(waves) ' wavelengths and ' int2str(t) '/100 \tau']);
    xlabel('Distance');
    ylabel('E field');
    legend('Ei', 'Er', 'Combined');
	M(t) = getframe; %This animates the series of graphs.
end