title: Computational complexity of Inverse FFT
body: <p>I am trying to calculate the computational complexity of ifft, I know it’s NlogN for a N*1 dimension, signal. But I have a product of two signals then I want to get ifft, and then calculate the computational complexity. So simply, if X(w) and Q(w) are Fourier transform of two time signal , then what is computational complexity of their product.<br>
  Note: X(w) and Q(w) has same (N*1) size.<br>
  ifft(X(w)*Q(w))=???  </p>