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Questions tagged [dft]

Discrete Fourier transform (DFT) is a specific kind of discrete transform, used in Fourier analysis.

Given a sequence of N samples f(n), indexed by n = 0..N-1, the discrete Fourier transform (DFT) is defined as F(k), where k=0..N-1:

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Source: engineeringproductivitytools

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How to assess image quality using image comparison

I would like to compare videos. To compare the quality (Non blurry) by coding a C program. Someone told me to learn about DFT (Discrete Fourier Transform) for image analysis and to use a FFT or DFT tool to learn the difference between blurred vs…
Meganathan
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1d complex to complex transform with cuda cufft library

i'm writing a simple code for complex to complex 1d FFT with cuda library "cufft". I've changed "cudaMalloc" with "malloc" because if i use cudaMalloc exe file not work and crashing! But this is not the primary problem. When i execute the program,…
Marco Jammajalla Mangraviti
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If signal sample length is N, it can stand for at most N/2 + 1 kinds of frequencies

How to prove the statement in the title? Here is how I understand it. Let's say we have 10 samples. Signal Peak: 1, 3, 5, 7, 9 Signal Valley:2, 4, 6, 8, 10. Frequencies we can extract from it is: (What are in the bracket are the waveform) freq…
hellocoding
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how to apply window function on PCM signal?

can anyone please explain me or give some source for "how to properly apply 32 window function on a PCM signal ? I need this to perform fft on audio signal , but couldnt find out a proper way of doing it !
Malith Shivantha Weerarathne
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how to do 2-D fft of a big matrix efficiently

a 8000*8000 matrix (Channel Impulse Response) --> Ht frequency domain : Hf=F*Ht*F' (F is DFT matrix --> http://en.wikipedia.org/wiki/DFT_matrix ) the problem is it takes too much time to do so,is there any solution for this?
Li_Xia
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How to write C code for a long signal and long kernel convolution

I would like to do a linear convolution for a signal of length 4000*270, with a kernel of length 16000. The signal is not fixed while the kernel is fixed. This needs to be repeated for many times for my purpose, so I want to improve the speed as…
Ashley
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How to Plot fft of ascii values in MATLAB?

I have a ascii file containing 2048 x and y value pairs. I just want to know how to plot fft of y in MATLAB. I am writing following MATLAB code but could not be able to find appropriate result. How can I do this? This is what I have tried: I =…
Neerajiitb
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Nested loops of DFT in matlab

Can someone explain these nested loops of DFT in matlab: N=length(x); for k=1:N X(k)=0; for n=1:N X(k)=X(k)+x(n).*exp(-1j.*2.*pi.*(n-1).*(k-1)./N); end end
noman saeed
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