The BLOCK function forms a block-diagonal matrix. The blocks are defined by the arguments to the function. Up to 15 matrices can be specified. The matrices are combined diagonally to form a new matrix.
For example, if 
, 
, and 
are any matrices, then the block matrix formed from these matrices has the following form:
![\[ \left[ \begin{array}{ccc} A & 0 & 0 \\ 0 & B & 0 \\ 0 & 0 & C \end{array} \right] \]](images/imlug_langref0122.png)
The following statements produce a block-diagonal matrix composed of three blocks, shown in Figure 23.51:
a = 1;
b = {2 2,
3 3};
c = {4 4 4,
5 5 5};
d = block(a, b, c);
print d;