cyclic_autocovariance_fast.m

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function R=cyclic_autocovariance_fast(x,T,max_tau)
%
% CYCLIC_AUTOCOVARIANCE_FAST
%              
%              calculates the cyclic autocovariance for signal x
%              at frequency alpha=1/T using a fast
%              approximation based on the synchronous average of the
%              time varying autocorrelation.  Fundamental signal
%              period can be defined as a single period or as a sequence
%              of once per period pulse times.
%             
%              R(k*alpha,tau)=E{ x(t-tau/2) y(t+tau/2)
%                                exp(-jk(alpha)t)}
%              for k=0 ... 1/alpha
%              Signals x has its periodic average removed
%
% USAGE
%              R=cyclic_autocovariance_fast(x,T,max_tau)
%
%              calculate autocorrelation up to max_tau time lags
%
%              if T is a scalar, then T defined the fundamental
%              cyclic period
%
%              if T is a vector, then T defines a series of once
%              per revolution impulses

% File: cyclic_autocovariance_fast.m
% Last Revised: 24/11/97
% Created: 24/11/97
% Author: Andrew C. McCormick
% (C) University of Strathclyde

R=cyclic_cross_covariance_fast(x,x,T,max_tau);