How make line coding in matlab

i have problem with code to make line coding miller. I use this program.

Please help me with a solution.

clc
clear all
l=20;
a=rand(1,l);
a=round(a);
l=length(a);
t=0:(length(a))-1
for i=3:length(a)
    b(2*i-1)=a(i)
    b(2*i)=a(i)
    if a(i)== 1 
    mill(2*i-1)=1*(mill(2*i-2));
    mill(2*i)=-1*mill(2*i-2);
    else if a(i)==0 & a(i-1)==0 
    mill(2*i-1)=-1*(mill(2*i-2));
    mill(2*i)=-1*mill(2*i-2);
    else
    mill(2*i-1)=-1;
    mill(2*i)=1;
    end       
    end
end
t1=0:(length(b)-1)
subplot(3,1,1)
 stairs(t,a)
ylabel('amplitude')
xlabel('temps')
title('Code A')
axis([0,length(a),-5,5])
grid
subplot(3,1,2)
stairs(t1,b)
ylabel('amplitude')
xlabel('temps')
title('signal binaire B')
axis([0,length(b),-5,5])
grid
 subplot(3,1,3)
 stairs(t1,mill)
ylabel('amplitude')
xlabel('temps')
title('Code miller')
axis([0,length(b),-5,5])
grid

[madhan ravi]

you can select your code and press the code button so that it‘s easy to read

[Image Analyst]

What is "line coding miller"? I don't know how to make it until I know what it is.

[aboubakr ouldja]

[madhan ravi]

aboubakr ouldja's answer moved here for consistency:

the erore message

??? Undefined function or method 'mill' for input arguments of type 'double'.

Error in ==> miller at 12

mill(2*i-1)=1*(mill(2*i-2));

Answer 1

[madhan ravi]

You haven't defined any variable named mill.

P.S - I have no idea what your trying to do though..