1.  +. -. *. /都會激發廣播機制

>>> s
array([[1],
       [2],
       [3]])
>>> ss
array([[1, 2],
       [3, 4],
       [5, 6]])
>>> s
array([[1],
       [2],
       [3]])
>>> ss + s
array([[2, 3],
       [5, 6],
       [8, 9]])
>>> ss - s
array([[0, 1],
       [1, 2],
       [2, 3]])
>>> ss * s
array([[ 1,  2],
       [ 6,  8],
       [15, 18]])
>>> ss / s
array([[1.        , 2.        ],
       [1.5       , 2.        ],
       [1.66666667, 2.        ]])
 

• 標量vs向量/矩陣
• 會自動擴充套件至緯度相等(此處標量->(3, 1))

>>> s
array([[1],
       [2],
       [3]])
>>> s + 1
array([[2],
       [3],
       [4]])
>>> s - 1
array([[0],
       [1],
       [2]])
>>> s * 2
array([[2],
       [4],
       [6]])
>>> s / 2
array([[0.5],
       [1. ],
       [1.5]])
 

• 向量vs矩陣
• 會自動擴充套件至緯度相等(此處向量->(3, 2))
• 必須要有一個維度是相等的才會發生廣播，否則報錯

>>> s
array([[1],
       [2],
       [3]])
>>> ss
array([[1, 2],
       [3, 4],
       [5, 6]])
>>> s
array([[1],
       [2],
       [3]])
>>> ss + s
array([[2, 3],
       [5, 6],
       [8, 9]])
>>> ss - s
array([[0, 1],
       [1, 2],
       [2, 3]])
>>> ss * s
array([[ 1,  2],
       [ 6,  8],
       [15, 18]])
>>> ss / s
array([[1.        , 2.        ],
       [1.5       , 2.        ],
       [1.66666667, 2.        ]])