Periodic signal revisited

1. I am considering my example x=cos2t from 0 to 5pi used in the previous homework part 1.E.

Ct ECE301Fall2008mboutin.jpg

sampled at 0.01

Dt0 ECE301Fall2008mboutin.jpg

but converting it to DT and increasing the sampling rate to 0.08 shows a non-periodic set of points

Untitled12 ECE301Fall2008mboutin.jpg

2. for making a periodic siganl lets take an example of $ X=\ e^t $

the graph of the function is

Nonperiodic12 ECE301Fall2008mboutin.jpg

to convert it to periodic we use the following matlabcode

%referred the code of paul sceffler
clc
clear

t=.01:.01:1;
x=exp(t);
i=[];
for d=1:5
    i=[i,x];
end

t=[.01:.01:5];
plot(t,i)

the periodic function thus is

Periodic12 ECE301Fall2008mboutin.jpg

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