This applet gives a visualization of the operation of addition of matrices.
In the panel below, select p, the number of rows, and q, the number of columns
from the drop down menu and click OK.
This will generate two matrices of order p x q. Now, click the Start button at the bottom
of the panel. This present two method of visualization. You can select
'Demo' to see step-by-step evaluation of the entries of the sum of the two matrices.
You can select 'Custom' which allows you to compute any
particular entry of the sum.