numpy covariance matrix

Question

Suppose I have two vectors of length 25, and I want to compute their covariance matrix. I try doing this with numpy.cov, but always end up with a 2x2 matrix.

Answer 1

I suppose what youre looking for is actually a covariance function which is a timelag function. I'm doing autocovariance like that:

 def autocovariance(Xi, N, k):
    Xs=np.average(Xi)
    aCov = 0.0
    for i in np.arange(0, N-k):
        aCov = (Xi[(i+k)]-Xs)*(Xi[i]-Xs)+aCov
    return  (1./(N))*aCov

autocov[i]=(autocovariance(My_wector, N, h))