Question about FFT

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itsik
itsik 2011-6-9
回答： Saee 2014-11-6
hello to all
supposed that i have a matrix of 10 values [1x10]
and i want to sample it by IFFT to get 1000 samples ,i get a matrix of [1x1000]
and when i want to receive the same 10 values back by FFT
im getting a matrix of [1x1000] ,how do i get the 10 original values back ???
thank alot

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回答（2 个）

Honglei Chen
Honglei Chen 2011-6-9
Hi itsik,
When you do IFFT to get 1000 samples, it simply pads zero at the end. So when you do fft back, just take the first 10 samples.
x = rand(1,10);
y = fft(ifft(x,1000));
[x;y(1:10)]
HTH,
Honglei
Saee
Saee 2014-11-6
I have a vector of discrete data( they show the positions in single time), I am using fft to see how this data behaves in terms of periodicity? all example I found in matlab talk about the sample frequency and sample length , I know that the sample length can be the length of my vector ,but how the sample frequency plays role here ? will you please give me some helps by answering my question?

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