Fourier transform how to get coefficients

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Vincent Sin
Vincent Sin 2018-12-15
评论： Star Strider 2018-12-15
Hey everyone, i know that matlab have the method for fourier transform implemented but i was wondering if there is anything that could give me coefficients of fourier transfrom.

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Star Strider
Star Strider 2018-12-15
With the MATLAB fft function, at each frequency, the real value is the cosine coefficient, and the imaginary value is the sine coefficient.
At least that is how I understand it.
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Vincent Sin
Vincent Sin 2018-12-15
And how would you understand that we should use only 1/3 of values to draw that picture?
Star Strider
Star Strider 2018-12-15
You can use any subset you like. This is just an example.
Another option might be to take an arbitrary subset of the transformed matrix:
idx = randperm(numel(P), fix(numel(P)/3));
sbs = ind2sub(size(Y), idx);
S = false(size(Y));
S(sbs) = 1;
Ys = Y.*S;
P2 = ifft(Ys);
figure
imagesc(abs(P2))
Try this on the original and the ‘Y’ array after using fftshift.

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madhan ravi
madhan ravi 2018-12-15
real()
imag()

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