For example, there is a very long-term observation and I cut the signal at a sampling rate of
10 into many segments of
1e6-point length. I wanna check the time-varying characteristics of the spectrum, so I fft each segment and compare their spectrum.
When doing the fft for each
1e6-point segment, in case of
y = fft(x, 2^nextpow2(1e6)=1048576), we get the spectrum at freqs = 0 : 9.5367e-06 : 5 Hz. But it's time-consuming and I don't wanna store such big data.
So what if
y = fft(x, 1024)? Do I get the CORRECT spectrum for freqs = 0 : 0.0098 : 5 Hz?