How to interpret the image made by using FFT function directly

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星辰慕 2020-9-28

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关闭： MATLAB Answer Bot 2021-8-20

For this kind of picture, I'd like to know what it means. I just import a column of data into Matlab, make this column as X, and then directly use y = FFT (x); plot (y) to get the image

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Answer 1

Ameer Hamza 2020-9-28

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编辑：Ameer Hamza 2020-9-28

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Generally, fft of a real-values vector contain complex values. When you directly use

y = fft(x)
plot(y)

It just plots real components (x-axis) against complex components (y-axis). I am not sure if this gives any useful information. The usual way is to plot the abs() of the fft vector which gives information about frequency response.