Question

Which of the following operation is done on the sequence in least square design method?

(a) Convolution

(b) DFT

(c) Circular convolution

(d) Correlation

This question was addressed to me at a job interview.

This intriguing question comes from Least Squares Design Methods topic in section Digital Filters Design of Digital Signal Processing

Answer 1

Correct choice is (d) Correlation

For explanation I would say: In a practical design problem, the desired impulse response hd(n) is specified for a finite set of points, say 0 < n <L where L ≫ N. In such a case, the correlation sequence can be computed from the finite sequence hd(n).