MATLAB: Value of J in DFT

dftfft

Hi,

I am going through a post for DFT code in matlab so that I can convert it to JAVA. while going through I found below link. http://www.mathworks.com/matlabcentral/answers/67283-need-fft-code-for-matlab-not-built-in

Might be this is done long back. But I see Sum=Sum+x(jj)*exp(-2*pi*j*(jj-1)*(k-1)/nfft);

In this after pi, there is "j" what is the value of J here and how can I determine that.

Thanks in advance for your support!!

Best Answer

j (along with i) is the imaginary unit. In the Command Window, type

 >> j
 ans =
   0.0000 + 1.0000i

See http://www.mathworks.com/help/matlab/ref/i.html for details.

Related Solutions

MATLAB: Difference between fft and pspectrum

The 'fft(x)' function computes the discrete Fourier transform (DFT) of x using a fast Fourier transform (FFT) algorithm.

Please refer the following link for more information about the fft function.

https://in.mathworks.com/help/matlab/ref/fft.html

The 'pspectrum(x)' function returns the power spectrum of x.

Please refer the following link for more information about the 'pspectrum' function.

https://in.mathworks.com/help/signal/ref/pspectrum.html?s_tid=srchtitle

A fast Fourier transform is an algorithm that computes the discrete Fourier transform of a sequence. Fourier Transform changes the domain of the signal from time or space to frequency domain. The DFT is obtained by decomposing a sequence of values into components of different frequencies.

The statistical average of a certain signal or sort of signal (including noise) as analyzed in terms of its frequency content, is called its spectrum. So, the power spectrum refers to the spectral energy distribution that would be found per unit time, since the total energy of such a signal over all time would generally be infinite.

MATLAB: DFT

Hi Lisa, you had a couple problems with your code:

N= 4; 
x=1:4;
for k=0:3
    for n = 0:3;
y(n+1) = x(n+1).*exp(-(1j*2*pi*k*n)/N);
    end
    xdft(k+1)= sum(y);
end

compare to

fft(x)

Best Answer

Related Solutions

MATLAB: Difference between fft and pspectrum

MATLAB: DFT

Related Question