Arduino FFT noobie question How do you obtain the real and imaginary parts of a signal using FFT in arduino?
I could not find a particular tutorial with code for this purpose in the internet.
Most libraries will either take one array of samples as input and then fill two other arrays of real and imaginary data, or it will take one array of samples and one empty array as input, and the sample data will be replaced by the real data and the empty array filled with the imaginary data.

You will have to first choose a library to use and then read the examples or documentation to see what the format of the functions are.