累乘

a = np.array([1, 2, 3, 4])
b = np.prod(a)  # 24
c = np.cumprod(a)  # [ 1,  2,  6, 24]

累加

a = np.array([1, 2, 3, 4])
b = np.sum(a)  # 10
c = np.cumsum(a)  # [1, 3, 6, 10]