# What is a Vampire Matrix?

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Apply for a paid internship at Jane Street! Or, a job.
https://www.janestreet.com/join-jane-street/info-booth/

Vampire Numbers on Numberphile with James Grime.
https://youtu.be/3ZMnVd4ivKQ

Flammable Math’s original tweet:

Robin Houston gets involved:

Here comes Greg Egan!

Robin’s tweets about characteristic polynomials and the Cayley-Hamilton theorem. I suggested looking them up and working through the logic yourself. It’s straight-forward enough and good fun.

Robin’s code for finding 2 × 2 examples:
https://gist.github.com/robinhouston/83f0fa99046aeaaf5d27ddbb3218142e

Robin’s 3 × 3 monsters. If you can beat them: let us know!

Behold the pi matrix which squares to give more pi!
[[15,143],[52,936]]
https://www.wolframalpha.com/input/?i=%5B%5B15%2C143%5D%2C%5B52%2C936%5D%5D%5E2

CORRECTIONS
– At 07:20 I say 81 when I mean 82. The on-screen number is correct.
– I accidentally say "log troll" instead of "division troll" at 03:38.
– At 03:45 I cross out the wrong 7. Whoops. Gives 117 instead of 171. First spotted by Ryan Parker (no relation).
– I think that’s all. Let me know if you spot any more mistakes.

As always: thanks to Jane Street who support my channel. They’re amazing.
https://www.janestreet.com/

And thanks to all my Patreon legends. Your support paid for that cape. Let me know if you have any other video ideas I can use it for.
https://www.patreon.com/standupmaths

Spoooky wardrobe, make-up, filming and editing by Alex Genn-Bash
Spoooky maths animations by Matt Parker
Extra-spoooky music by Howard Carter
Largely non-spooky design by Simon Wright and Adam Robinson

MATT PARKER: Stand-up Mathematician
Website: http://standupmaths.com/
US book: https://www.penguinrandomhouse.com/books/610964/humble-pi-by-matt-parker/
UK book: https://mathsgear.co.uk/products/5b9fa76f230ffa140094dc43
Nerdy maths toys: http://mathsgear.co.uk/