At a team meeting last Thursday, two guys from my group came wearing similar shirts:

The key difference we all noticed was the way the stripes were different. We declared the stripes to be the inverse of each other.
And our principle engineer suddenly said "Then together you are an identity matrix!"
To which, the response was chiefly "I cannot believe you just said that!" and "Once a nerd, always a nerd" and other similar things of that sort. There was also a great deal of laughing.





In case you are wondering a matrix multiplied by its inverse matrix produces an identity matrix.

For example, if I had a 2x2 matrix (called A) like this: [1 2
3 4]
the inverse (called A^-1 would be: 1/(1*4 - 2*3) X [4 -2
-3 1]

Multiply the two (A*A^-1) gives you the identity matrix (called I): [1 0
0 1]
Ones run all down the diagonal of an identity matrix, while the rest of the spaces are filled with zeros.

For a better and more clear explanation visit Wolfram MathWorld
. They can definitely explain much clearer than I just did.