function gauss(sigma_k,kbar)
lam = 2*pi/kbar;
dx = lam/20;
sigma_x = 1/sigma_k;
x = -5*sigma_x:dx:5*sigma_x;
xi = sigma_k*x;
env = exp(-0.5*xi.^2);
eta = cos(kbar*x).*env;  % wave at t=0
plot(xi,env,'r',xi,-env,'g',xi,eta)
texText('$\xi$','x')
xticks(-5:5)
graphToPDF('gauss.pdf',4.25,2)
end