generates cross-covariance function.
[C,N,LAGS] = nan_xcovf(X,MAXLAG,SCALEOPT) [C,N,LAGS] = nan_xcovf(X,Y,MAXLAG,SCALEOPT)
XCOVF is the same as XCORR except X and Y can contain missing values encoded with NaN. NaN's are skipped, NaN do not result in a NaN output. The output gives NaN only if there are insufficient input data
[C,N,LAGS] = nan_xcovf(X,MAXLAG,SCALEOPT); calculates the (auto-)correlation function of X
[C,N,LAGS] = nan_xcovf(X,Y,MAXLAG,SCALEOPT); calculates the crosscorrelation function between X and Y