Using the DFT

sampling $sin(2*pi*t)$ and taking the DFT we get this graph:

Script for matlab: clear all;

t=0:.01:1;

T=0.20;

ts=0:T:1;

f1=2;

f2=1/0.125;

x = sin(2*pi*3*t); %this is the function

plot(t,x); % plot the original signal

X = fft(x); % take the DFT

pause (2);

plot (t,X); %plot the DFT of the signal