인공지능 수학 - 선형대수 (NumPy 실습)
행렬과 벡터의 코딩 및 연산## 인공지능 수학 - 선형대수 (NumPy 실습)
import numpy as np
A = np.array([[1,2,3],[4,5,6],[7,8,9]])
print(A)
print(A.shape)
>>>[[ 3 1 1]
[ 1 -2 -1]
[ 1 1 1]]
>>>(3, 3)
b = np.array([4, 1, 2])
print(b)
print(b.shape)
>>>[4 1 2]
>>>(3,)
A_inv = np.linalg.inv(A)
print(A_inv)
print(A_inv.shape)
>>>[[ 5.00000000e-01 -7.40148683e-17 -5.00000000e-01]
[ 1.00000000e+00 -1.00000000e+00 -2.00000000e+00]
[-1.50000000e+00 1.00000000e+00 3.50000000e+00]]
>>>(3, 3)
x = A_inv @ b
print(x)
print(x.shape)
>>>[ 1. -1. 2.]
>>>(3,)
bb = A @ x
print(bb.shape)
print(bb)
if np.linalg.norm(b - bb) < 1e-3:
print("ok")
else:
print("something wrong")
>>>(3,)
>>>[4. 1. 2.]
>>>
ok