[tmyklebu]

> The converse is also true (and is much easier to prove, so we won’t be concerned with it): a diagonalizable matrix is always normal.

It is actually more difficult to prove. [2, 1; 0, 1] is diagonalisable (via [1, -sqrt(2)/2; 0, sqrt(2)/2]) but not normal.

[michael_nielsen]

I mean diagonalizable by a unitary matrix. Fixed.

[Escapado]

I never knew you were on HN but I'll use this opportunity hoping that you'll read this. Recently I finished my masters thesis in quantum machine learning (I'm a physicist) and I think without the amazing book you wrote with Isaac Chuang I would not have been able to do it. So this is meant as a huge thank you! I tried other QC books but I found yours the most insightful and approachable.

On another note I also enjoy your essays on SRS and it encouraged me to start learning Japanese using it.

[fhars]

You might also want to mention early that when you talk about the length of a row or column, you do not mean its (thanks, Apple, for autocorrecting that to it’s) length (i.e. number of elements), but its L2 norm. That just caused me to lose half an hour...