Custom DFT function for even and odd samples

I'm trying to create a custom DFT function using circshift for even and odd samples but the odd part is not working. I appreciate if someone can help.

function X_k = my_DFT(x,N)

L = length(x);

if N < L
    error(' N < L')
elseif N > L
    xn = zeros(1,N); %zero padding
    xn(1:L) = x;
else % N == L
    xn = x;
end



if rem(N, 2) == 0 
n = 0 : N-1;
k = 0 : N-1;

CoefMatrix = exp(1i * (2*pi/N) * k' * n);

X_k = CoefMatrix * xn';

X_k = circshift(X_k',N/2);
else

n = 0 : N-1;
k = 0 : N-1;
CoefMatrix = exp(1i * (2*pi/N) * k' * n);
X_k = CoefMatrix * xn';

X_k = circshift(X_k',N/2 + 1); %?

end

end

[Mohammed Samir]

l=length(x);

if(l<N)

x=[x zeros(1,(N-1))];

else if(l>=N)

x=[x(1:N)];

end

[WarriorPlatypus]

Excuse me I dont think this would work...

Answer 1

[Nadia Shaik]

Hello,

It is my understanding that you are trying to create a custom DFT function for even and odd samples of the input using circshift function.

You may refer to the below mentioned code example:

function X_k = my_DFT(x,N)
L = length(x);
if N < L
    error(' N < L')
elseif N > L
    xn = zeros(1,N); %zero padding
    xn(1:L) = x;
else % N == L
    xn = x;
end
if rem(L, 2) == 0 
n = 0 : N-1;
k = 0 : N-1;
CoefMatrix = exp(1i * (2*pi/N) * k' * n);
X_k = CoefMatrix * xn';
X_k = [X_k(1) circshift(X_k(2:end)',N-1)];
else
n = 0 : N-1;
k = 0 : N-1;
CoefMatrix = exp(1i * (2*pi/N) * k' * n);
X_k = CoefMatrix * xn';
X_k = circshift(X_k',N); %?
end
end

I hope it helps you.