Time for action – creating a matrix from other matrices

We will create a matrix from two smaller matrices as follows:

1. First, create a 2-by-2 identity matrix:

   A = np.eye(2)
   print("A", A)

   The identity matrix looks like the following:

   A [[ 1.  0.]
    [ 0.  1.]]
   

2. Create another matrix like A and multiply it by 2:

   B = 2 * A
   print("B", B)

   The second matrix is as follows:

   B [[ 2.  0.]
    [ 0.  2.]]
   

3. Create the compound matrix from a string. The string uses the same format as the mat() function—use matrices instead of numbers:

   print("Compound matrix\n", np.bmat("A B; A B"))

   The compound matrix is shown as follows:

   Compound matrix
   [[ 1.  0.  2.  0.]
    [ 0.  1.  0.  2.]
    [ 1.  0.  2.  0.]
    [ 0.  1.  0.  2.]]
   

What just happened?

We created a block matrix from two smaller matrices with the bmat() function. We gave the function a string containing the names of matrices instead of numbers (see bmatcreation.py):

from __future__ import print_function
import numpy as...