signal processing - Differences in types of FFT? -


i want clarify on difference between 'implementations of fft'. ive read there 1d ffts , there 2d ffts , others.

may know differences regarding these (e.g. input, output, etc.). example, dimension fft uses input of arr[n*2] = real , arr[n*2+1] = imaginary?

also, use of complex[] fft algorithms? noticed use x , y during fft algorithm. real , imaginary?

thanks!

the fft can have number of dimensions, 1d ffts commonly used data inherently 1 dimensional, e.g. audio, , 2d ffts used 2d data such images.

in general case both input data , output data complex, i.e. there real , imaginary components in each input/output value. "real world", i.e. physical, data imaginary part of input data zero. output of fft though, purely real input data, have both real , imaginary components.

depending on fft implementation, input/output data may interleaved arrays, real components @ 2*i , imaginary components @ index 2*i+1, or may use complex data type, or real , imaginary components may in separate arrays. api detail though, underlying algorithm still same.


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