Applied mathematics, numerical linear algebra and software.

Fifty “What Is” Articles

Last week I posted the fiftieth in my “What Is” series of articles. I began the series just over a year ago, in March 2020. The original aim was to provide “brief descriptions of important concepts in numerical analysis and related areas, with a focus on topics that arise in my research”, and the articles were meant to be short, widely accessible, and contain a minimum of mathematical symbols, equations, and citations. I have largely kept to these aims, though for some topics there is a lot to say and I have been more lengthy.

The articles are also available in PDF form on GitHub.

Below is a list of all the “What Is” articles published at the time of writing, in alphabetical order.

If there is a topic you would like me to cover, please put it in the comments below.

Dear Professor Higham,
I would like to read from you about “totally positive matrices” (a subject related to some of your classical contributions; I recall my comment in your post “Conference in Honour of Walter Gautschi”).
Thank you for your work.

These are such a brilliant resource, Nick. Thank you.

What about “what is rank revealing decomposition”? it could be an interesting and useful topic. Tks

Dear Professor Higham,

I would like to read from you about “totally positive matrices” (a subject related to some of your classical contributions; I recall my comment in your post “Conference in Honour of Walter Gautschi”).

Thank you for your work.