Understanding matrices intuitively, part 1 by William Gould.
From the post:
I want to show you a way of picturing and thinking about matrices. The topic for today is the square matrix, which we will call A. I’m going to show you a way of graphing square matrices, although we will have to limit ourselves to the 2 x 2 case. That will be, as they say, without loss of generality. The technique I’m about to show you could be used with 3 x 3 matrices if you had a better 3-dimensional monitor, and as will be revealed, it could be used on 3 x 2 and 2 x 3 matrices, too. If you had more imagination, we could use the technique on 4 x 4, 5 x 5, and even higher-dimensional matrices.
Matrices are quite common in information retrieval texts.
William’s post is an uncommonly good explanation of how to think about and picture matrices.
I first saw this in Christophe Lalanne’s A bag of tweets / May 2013.