function graphError2(ka)
xi = 2*pi*(0:0.01:1)';
S = sin(xi);

eta = NaN(length(xi),3);  % really eta/a
eta(:,1) = -S;                                            %   zero order
eta(:,2) = -(S+0.5*ka)./(1+ka*S);                         %  first order
eta(:,3) = -S - 0.5*ka*(1-2*S.^2) + 0.5*ka^2*(S-3*S.^3);  % second order
ez   = exp(ka*eta);

K     = [0, -0.5*ka, -0.5*ka];   %[zero order, first order, second order]
rat   = [1, 1, 1/(1-ka^2)];
LHS_D = rat.*ez.*(S + 0.5*ka*ez)+eta;
LHS_K = -K + ez.*S + eta;

figure(3)
    plot(xi/(2*pi),100*LHS_D)
    texText(sprintf('Dynamic BC error: $ka = %0.2f$',ka),'t')
    texText('$\xi/2\pi$','x')
    texText('error [\%]','y')
    legend({'(ka)^0','(ka)^1','(ka)^2'},'location','southeast','box','off')
    graphToPDF(sprintf('errorD%0.2f.pdf',ka),4.25,3)

figure(4)
    plot(xi/(2*pi),100*LHS_K)
    texText(sprintf('Kinematic BC error: $ka = %0.2f$',ka),'t')
    texText('$\xi/2\pi$','x')
    texText('error [\%]','y')
    legend({'(ka)^0','(ka)^1','(ka)^2'},'location','southeast','box','off')
    graphToPDF(sprintf('errorK%0.2f.pdf',ka),4.25,3)
end