Eye diagram: Redefining a variable?

I'm doing a MATLAB exercise to generate eye diagrams of different digital waveforms for a digital comm. course. The program is written in the text book, I just need to understand this one command:

yrz = yrz(1:end-Tau+1);

The whole program:

%(pnrz.m)

%generating a rectangular pulse of width T

function pout=prect(T);

pout=ones(1,T);

end

%(prz.m)

% genrating a rectangular pulse of width T/2

function pout=prz(T);

pout=[zeros(1,T/4) ones(1,T/2) zeros(1,T/4)];

end

%(psine.m)

% generating a sinusoid pulse of width T

function pout=psine(T);

pout=sin(pi*[0:T-1]/T);

end

%(binary_eye.m)

% generate and plot eyediagrams

clear;clf;

data = sign(randn(1,400)); %Generate 400 random bits

Tau=64; %Define the symbol period

dataup=upsample(data, Tau); %Generate impulse train

yrz=conv(dataup,prz(Tau)); %Return to zero polar signal

yrz=yrz(1:end-Tau+1);

ynrz=conv(dataup,pnrz(Tau)); %Non-return to zero polar

ynrz=ynrz(1:end-Tau+1);

ysine=conv(dataup,psine(Tau)); %half sinusoid polar

ysine=ysine(1:end-Tau+1);

eye1=eyediagram(yrz,Tau,Tau,Tau/2);title('RZ eye-diagram');

eye2=eyediagram(ynrz,Tau,Tau,Tau/2);title('NRZ eye-diagram');

eye3=eyediagram(ysine,Tau,Tau,Tau/2);title('Half-sine eye-diagram');

[Jan]

Please follow the "? Help" link to learn how to format code in this forum. Thanks.

Answer 1

[Pourya Alinezhad]

the code dose not work on my pc. because prz and psin ,... functions are not provided with the code. following code: yrz = yrz(1:end-Tau+1); removes one symbol length data from yrz's end.

[Mohamed Ali]

Thank you!