Efficient Calculation of Complex Analytic IFFT

Started by nadavf May 11, 2005
Hi All,

My question is as follows. When calculating an N-point IFFT with the
inputs conjugate symmetric (real output), this can be performed using a
single N/2-point IFFT and some pre and post processing.

Is there any method to do this (use a single N/2-point IFFT) with half the
inputs set to zero instead of the complex conjugate? (and thus getting the
complex analytic output instead of the real output?)

Thanks, Nadav



		
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nadavf wrote:
  > Is there any method to do this (use a single N/2-point IFFT) with 
half the
> inputs set to zero instead of the complex conjugate? (and thus getting the > complex analytic output instead of the real output?) > > Thanks, Nadav
I won't call it impossible ... but I doubt it. Look at the inverse operation that would be possible if that were true. It would be equivalent to zero-padding a length N sequence to size 2N and doing a 2N fft on it for the cost of a 1N fft. In other words, you'd get the increased/interpolated frequency resolution for free. -- Mark