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christianp.mathstodon.xyz.ap.brid.gy
Christian Lawson-Perfect
@christianp.mathstodon.xyz.ap.brid.gy
88 followers 5 following 640 posts
Mathematician, koala fan, mathstodon.xyz admin,
⅓ of https://aperiodical.com. He/him

[bridged from https://mathstodon.xyz/@christianp on the fediverse by https://fed.brid.gy/ ]
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christianp.mathstodon.xyz.ap.brid.gy
yum
https://tilingsearch.mit.edu/HTML/data156/F31.html
A tiling using five-pointed stars, regular pentagons, a couple of kinds of quadrilateral and 10-pointed stars.
November 11, 2025 at 12:56 PM
christianp.mathstodon.xyz.ap.brid.gy
It's getting towards the end of the year and I was only on April of my page-a-day notepad, so of course I had to make an origami dodecahedron.
A dodecahedron made from origami units, sitting on my desk. The two edges facing the camera have "Monday" and "Thursday" written on them.
November 9, 2025 at 9:53 AM
christianp.mathstodon.xyz.ap.brid.gy
Good deed for the day done: I swept up the glass on the cycle path outside Spanish City that's been there for a week. It was a whole bottle's worth, across both lanes of the path.

Pity I then didn't have time to get my bike ride done, but at least I've had […]

[Original post on mathstodon.xyz]
Looking at the path, which is half cycle lanes and half footpath. The glass is spread across a stretch about 10m long, but I don't think it's very visible in this photo. A Tupperware full of shards of glass and pebbles, next to a dustpan and brush
November 7, 2025 at 1:31 PM
christianp.mathstodon.xyz.ap.brid.gy
Another day in Outlook: the "From" line is so long that it pushed the reply button off the edge.
part of the Outlook interface, showing the end of a very long email address, which is drawn on top of what looks like a single "smiley face" button and a three dots menu button, all above a timestamp.
November 7, 2025 at 10:01 AM
christianp.mathstodon.xyz.ap.brid.gy
Another kid told me that if you walk around its perimeter three times backwards at midnight, it'll tile periodically.
A big paper spectre monotile with a hi-viz outline, and a ghost face at the top. In the middle is written "spectre moan-o-tile"
October 31, 2025 at 4:42 PM
christianp.mathstodon.xyz.ap.brid.gy
Maybe this could work???
#beachspectres
3D rendering of a part of a wall, made from two curvy edges and a 90 degree corner, joined with dovetail joints.
October 28, 2025 at 4:30 PM
christianp.mathstodon.xyz.ap.brid.gy
#beachspectre ice cream?
A spectre monotile drawn so it looks like a 99 ice cream, with a waffle for the bottom half, white ice cream on top, and a chocolate flake for the sticky-out bit.
October 26, 2025 at 9:08 AM
christianp.mathstodon.xyz.ap.brid.gy
These are the pieces I need to make one spectre monotile. The good thing about them is that I can stack them together quite tightly when cutting out on a laser cutter, or each piece will fit on the bed of a 3D printer.

I still haven't decided whether laser […]

[Original post on mathstodon.xyz]
Six different shaped pieces: an S-shaped curve, one straight piece, and five different corners. There should be 14 curve, four convex right angles, five convex 120 degree corners, two concave 120 degree corners, two concave right angles, and one straight.
October 25, 2025 at 8:30 AM
christianp.mathstodon.xyz.ap.brid.gy
#beachspectres update: I'm taking it very seriously.
Segments of two curvy paths that join. Touching corners of the two paths are drawn in different colours, and have little smiley faces on because they're hugging.
October 24, 2025 at 3:17 PM
christianp.mathstodon.xyz.ap.brid.gy
The days are getting darker, so the bucket bike lights are back in action!

(yes, I'll ensure I comply with regulations when riding on the road...)

#cargobike #BikeTooter
October 21, 2025 at 7:07 AM
christianp.mathstodon.xyz.ap.brid.gy
Who decided to call it a tricorn and not an equihateral?
A three-cornered hat, as worn in the 1700s.
October 18, 2025 at 1:37 PM
christianp.mathstodon.xyz.ap.brid.gy
@julesh Birmingham New Street is a page from this book
Puzzle Town, from Usborne Young Puzzle Books
October 17, 2025 at 5:18 AM
christianp.mathstodon.xyz.ap.brid.gy
Uh oh, they're letting me use the laser cutter.
A small wooden lasercut spectre monotile held in my hand.
October 8, 2025 at 11:07 AM
christianp.mathstodon.xyz.ap.brid.gy
I shouldn't be allowed to use Blender.
A sandcastle in the shape of a spectre monotile, with a spectre-shaped flag flying from the top.
October 7, 2025 at 8:05 AM
christianp.mathstodon.xyz.ap.brid.gy
Brainwave: my office door is glossy white, so I can use it as a whiteboard!
A door with a diagram drawn on it in three bright colours
September 25, 2025 at 10:28 AM
christianp.mathstodon.xyz.ap.brid.gy
Today I watched a student, who hadn't spotted the trick in the puzzle we gave them, type 666^1024 into Google's calculator and get the answer "Infinity".
Fortunately for their future career in maths, they knew that was incorrect, but they were confused.
Is it […]

[Original post on mathstodon.xyz]
Screenshot of the Google calculator with the expression 666^1024 and a displayed result of Infinity.
September 18, 2025 at 4:49 PM
christianp.mathstodon.xyz.ap.brid.gy
Umm... how does this happen? @helvetica
Screenshot of Flipflop Solitaire with the game almost finished except there's an extra 4 of diamonds in play.
September 12, 2025 at 5:21 AM
christianp.mathstodon.xyz.ap.brid.gy
Happy birthday to my 5 year old.

The cake had to include a cat and a pigeon and the current obsession, Mallard - the fastest steam train.

I'm quite pleased with my effort! I particularly like the cheery passengers.
Looking down at a cake in the shape of a train carriage, with pigeons and cats made from royal icing sat in the windows. Looking down at three cake sections: a long piece in the shape of Mallard, a blue steam train; its blue tender carriage; and a brown passenger carriage with cat and pigeon passengers.
September 6, 2025 at 7:17 PM
christianp.mathstodon.xyz.ap.brid.gy
Who needs LLMs? This is an artisanal, handmade incorrect multiplication table.

(can you work out where I took this photo?)
A printed table. Read by rows: 1.00, 1m, 2m, 3m, 4m, 5m, 6m, 7m, 8m; 1m, 1, 2, 3, 4, 5, 6, 7, 8; 2m, 2, 3, 5, 7, 9, 11, 14, 16; ...
August 24, 2025 at 5:58 AM
christianp.mathstodon.xyz.ap.brid.gy
The "normal" maths kit is £4.50. The easy to read version, approved by the RNIB, IS £3.

Even if they were the same price, why would you ever not buy the easy to read version?

Apart from ableism, I mean.
Two Oxford maths kits on racks in Sainsbury's. Both are reduced in price. The normal kit is £4.50. The "visited n edition" kit is £3.
August 22, 2025 at 11:13 AM
christianp.mathstodon.xyz.ap.brid.gy
On our gather.town coffee call with @gavan and @mattp this morning, we noticed that the banner behind me could be completely solved, using a couple of well-known formulae and a reasonable boundary condition.
A conference banner with a logo that looks like the equation "E - A×M + S = 2018", above a whiteboard with some maths which is in the text of the post.
August 7, 2025 at 1:47 PM
christianp.mathstodon.xyz.ap.brid.gy
There was a bit of crossed wires about the birthday image thing, but it's all sorted out now and you can find an image with exactly (your birthday) black pixels at https://somethingorotherwhatever.com/matt-parker-count-black-pixels/birthday.html
Happy birthday! There are 010825 black pixels in this image. Your magic birthday word is 'wand'.
August 1, 2025 at 3:10 PM
christianp.mathstodon.xyz.ap.brid.gy
arghh, it's the end of the to-do list!
Run unit tests; Run eslint; Write release post
July 31, 2025 at 12:56 PM
christianp.mathstodon.xyz.ap.brid.gy
I am sat next to a train (carriage?) numbered 323232. That's noteworthy!
The front of a train, with the number 323232 below one headlight
July 29, 2025 at 6:27 PM
christianp.mathstodon.xyz.ap.brid.gy
A 3d printer and #freecad are so useful!

One of the clamp things on my bike basket snapped. It was really easy to design and print a replacement.

#3dprinting
July 27, 2025 at 8:23 AM