//Example 4_14_a
//determine the fourier series coeffient of x(n)
clc;
clear;
N=6;
n=0:0.01:N;
Wo=2*%pi/N;
xn=1*ones(1,length(n))+1*cos(Wo*n);
for k=0:N-2
C(k+1,:)=exp(-sqrt(-1)*Wo*n.*k);
a(k+1)=xn*C(k+1,:)'/length(n);
if(abs(a(k+1))<=0.1)
a(k+1)=0;
end
end
a=a';
a_conj=conj(a);
ak=[a_conj($:-1:1),a(2:$)];
Mag_ak=abs(ak);
k=-(N-2):(N-2);
plot2d3('gnn',k,Mag_ak,5)
xtitle('abs(ak)','k','ak')