Problem 43284. Form a square matrix from four square sub-matrices

Create a square matrix, y, from 4 square sub-matrices that will be constructed (x1, x2, x3, x4):

 y = [x1 x2;
      x3 x4];

The size of each sub-matrix will be n, while given values should be applied to each sub-matrix.

• 1st sub-matrix: n1 on the main diagonal with all other elements equal to 0
• 2nd sub-matrix: all elements equal to n2
• 3rd sub-matrix: all elements equal to n3
• 4th sub-matrix: same as the first but with diagonal elements equal to n4.

For example, with n=2, n1=1, n2=2, n3=3, and n4=5:

 y = [1 0 2 2;
      0 1 2 2;
      3 3 5 0;
      3 3 0 5];