A reader asked me about matrices, so I referred him to my series of Tutorials on Matrices and IR. He then asked me about some special kind of matrices. I answered his questions with some examples.  He then replied with some analogies.

Here is what I answered and his analogies (sort of). I guess he must be a graduate student on something.

1. Toeplitz Matrix (no, that isn’t Topless)

This is a matrix where all elements on superdiagonals and subdiagonals  are equal.

2. Hankel Matrix (no, that isn’t Hanky-Panky)

This is a matrix where all elements on any superdiagonal and subdiagonal perpendicular to the main diagonal are equal.

3. Vandermonde Matrix (no, that isn’t Banned on Monday)

A matrix where first column is 1’s succesive columns being the second column with its elements raised to increasing integer powers.

4. Idempotent Matrix (no, that isn’t impotence).

A matrix that when raised to an integer power remains the same.

Topless and Hanky-Panky banned on Monday due to impotence?