Compute covariance at various lags[=correlation(x-mean(x),y-mean(y))].
[c, lag] = moc_xcov (X [, Y] [, maxlag] [, scale])
input vector
if specified, compute cross-covariance between X and Y,
is specified, use lag range [-maxlag:maxlag],
n-1].
vector of lags
covariance for each lag in the range
Returns the covariance for each lag in the range, plus an optional vector of lags.