matlab code for line coding : unipolar, polar, bipolar and manchester code

%Matlab code to generate line code wave form  for given bit stream

clc;
close all;
clear all;
x=[1 0 1 1 0 1];
nx=size(x,2);
sign=1;
i=1;
while i<nx+1
    t = i:0.001:i+1-0.001;
    if x(i)==1
        unipolar_code=square(t*2*pi,100);
        polar_code=square(t*2*pi,100);
        bipolar_code=sign*square(t*2*pi,100);
        sign=sign*-1;
        manchester_code=-square(t*2*pi,50);
    else
        unipolar_code=0;
        polar_code=-square(t*2*pi,100);
        bipolar_code=0;
        manchester_code=square(t*2*pi,50);
    end
    subplot(4,1,1);
    plot(t,unipolar_code);
    ylabel('unipolar code');
    hold on;
    grid on;
    axis([1 10 -2 2]);
 
    subplot(4,1,2);
    plot(t,polar_code);
    ylabel('polar code');
    hold on;
    grid on;
    axis([1 10 -2 2]);
 
    subplot(4,1,3);
    plot(t,bipolar_code);
    ylabel('bipolar code');
    hold on;
    grid on;
    axis([1 10 -2 2]);
     
    subplot(4,1,4);
    plot(t,manchester_code);
    ylabel('manchester code');
    hold on;
    grid on;
    axis([1 10 -2 2]);
 
    i=i+1;

end