Plotting Mode Shapes/ Wave Function

I am trying to plot modes shapes, but my plot keeps appearing blank and I can't figure out what I'm doing wrong. Specifically, I am trying to plot position(x) as my x-axis, displacement(u) as my y-axis, and get a plot that appears sinusoidal. I have tried setting x = 1:0.5:5, but then I just get an error. What can I do to get this code to display a wave function like it should?

clear all;

format long;

im = sqrt(-1);

CellLength = 1;

ibeta = 1;

%Define materal properties 

CellLength = 1;

layers = 2;

d1 = 0.4; 

d2 = 0.6;

dTotal = d1+d2;

Ef = 12;

pf = 3;

cf = sqrt(Ef/pf);

Em = 1;

pm = 1;

cm = sqrt(Em/pm);

w = 5;

T1 = [cos(.2*w) (1/(6*w))*sin(.2*w); -6*w*sin(.2*w) cos(.2*w)];

T2 = [cos(.6*w) (1/w)*sin(.6*w); -w*sin(.6*w) cos(.6*w)];

T = T2*T1;

%Solve eigenvalue problem for k

[V,D] = eig(T);                 

k1 = log(D(1,1))/(im*dTotal);

k2 = log(D(2,2))/(im*dTotal);

B1 = [1 1; im*6*w -im*6*w];

a1 = inv(B1)*V(:,1);

x = 1;

u = [exp(im*k1*x) exp(-im*k1*x)]*a1;

plot(x,real(u))

Answer 1

[KSSV]

Replace last three lines by:

x = 1:0.5:5;
u = [exp(im*k1*x); exp(-im*k1*x)].*a1;
plot(x,real(u),'r')