I’m experiencing some strange behaviour, and I wonder if someone could explain it to me.
1) Take a signal with only real values (the ultrasonic burst used in “The first document”, for example)
2) Create a formula FFT(Burst)
3) Evaluate the formula – you now have a complex signal
4) Do an inverse FFT on that signal IFFT(Formula)
This should return the original signal, but does not! Due to rounding errors in the calculations I would expect a small imaginary component to the results, but the magnitude of the imaginary component is not small at all!
What am I missing here?