python numpy array 與matrix 乘方
阿新 • • 發佈:2018-06-28
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python numpy array 與matrix 乘方
編程語言 waitig 1年前 (2017-04-18) 1272℃ 百度已收錄 0評論數組array 的乘方(**為乘方運算符)是每個元素的乘方,而矩陣matrix的乘方遵循矩陣相乘,因此必須是方陣。
2*3的數組與矩陣
>>> from numpy import *
>>> import operator
>>> a = array([[1,2,3],[4,5,6]])
>>> a
array([[1, 2, 3],
[4, 5, 6]])
>>> m = mat(a)
>>> m
matrix([[1, 2, 3],
[4, 5, 6]])
>>> a ** 2
array([[ 1, 4, 9],
[16, 25, 36]])
>>> m ** 2
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "D:\anaconda\lib\site-packages\numpy\matrixlib\defmatrix.py", line 356, in __pow__
return matrix_power(self, other)
File "D:\anaconda\lib\site-packages\numpy\matrixlib\defmatrix.py", line 173, in matrix_power
raise ValueError("input must be a square array")
ValueError: input must be a square array
>>>
(mat()函數把array轉化為matrix)
3*3的數組與矩陣
>>> A = array([[1,2,3],[4,5,6],[7,8,9]])
>>> A
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> M = mat(A)
>>> M
matrix([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> A ** 2
array([[ 1, 4, 9],
[16, 25, 36],
[49, 64, 81]])
>>> M ** 2
matrix([[ 30, 36, 42],
[ 66, 81, 96],
[102, 126, 150]])
python numpy array 與matrix 乘方