from functools import reduce
def loopMult(Arr):
    ArrMult = Arr[0]
for i in range(1, len(Arr)):
    ArrMult = np.einsum('fij,fjk->fik', ArrMult, Arr[i])
return ArrMult

def myeinsum(A1, A2):
    return np.einsum('fij,fjk->fik', A1, A2)
A1 = loopMult(Arr)
A2 = reduce(myeinsum, Arr)
A3 = fmuls.multimul(Arr.T).T
print(np.allclose(A1, A2))
print(np.allclose(A1, A3))
Python, numpy, einsum умножают стек матриц