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//Example 14.1
//EFFECT OF DFT LENGTH ON SPECTRAL ANALYSIS
clear;
clc;
N=16;
n=0:N-1;
f1=0.22;
f2=0.34;
R = input("R point DFT(R E [16,128]) = "); //Input f1 = 64
if R >= N
x=0.5*(sin(2*%pi*f1*n')) + sin(sin(2*%pi*f2*n'));
x=[x',zeros(1,R-length(n))];
disp(x,'the sequence is :');
for n=0:R-1
for k=0:R-1
W(n+1,k+1) = exp(-(%i*2*%pi*k/R)*n);
end
end
X = W*x';
disp(X,'DFT is, X = ')
else
disp('invalid computation');
end
m=0:R-1;
clf();
figure(0)
a = gca();
plot2d3(m,abs(X),2) // plotting DFT of sequence
plot(m,abs(X),'r.')
a.x_location = 'origin';
a.y_location = 'origin';
poly1 = a . children (1) . children (1) ;
poly1.thickness = 2.5;
xtitle('original sequence','n','x[n]');
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