import numpy as np


X_1 = np.array([1, 1])
X_2 = np.array([2, 3])

def get_X_median(list_X):
    return np.mean(list_X, axis=0)

X_mediana = get_X_median([X_1, X_2])


def get_S(list_x):
    X_median = np.mean(list_x, axis=0)
    ans = np.zeros(shape=(len(list_x), len(list_x)))
    for ele in list_x:
        M = np.array(ele - X_median).reshape(-1,1)
        ans += M.dot(M.T)
    return ans / (len(list_x) - 1)

print(get_S([X_1, X_2]))