Custom DFT function for even and odd samples

Question

WarriorPlatypus 2021-4-20

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/807182-custom-dft-function-for-even-and-odd-samples

回答： Nadia Shaik 2022-2-3

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

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Mohammed Samir 2021-4-20

l=length(x);

if(l<N)

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

else if(l>=N)

x=[x(1:N)];

end

WarriorPlatypus 2021-4-20

Excuse me I dont think this would work...

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Answer 1

Nadia Shaik 2022-2-3

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/807182-custom-dft-function-for-even-and-odd-samples#answer_888080

在 MATLAB Online 中打开

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