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# Authored by Weisheng Jiang
# Book 4  |  From Basic Arithmetic to Machine Learning
# Published and copyrighted by Tsinghua University Press
# Beijing, China, 2022
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# Bk4_Ch4_11.py

from numpy.linalg import inv
A = np.array([[1., 2.], 
              [3., 4.]])

# matrix inverse
A_inverse = inv(A)
A_times_A_inv = A@A_inverse