Pinned toot

Hallo, new Mastodon users! Here on mathstodon.xyz we've got a couple of mathematical emoji: and . I'd love to add some more. If you can make a PNG image the same size as those, send it to me and I'll add it. Faces of famous mathematicians are an easy place to start; could we have some shapes, polyhedra, or other mathographics too?

Is this a nephroid?

The baby's stomach seems to be able to measure three hours to the second.
Is it too late to apply for the longitude prize?

Our second L-P is finally out. Early reviews describe him as "sleepy" and "cuddly".

I can't imagine what prompted this integer sequence: "Least multiple of n in which the n-th digit from left is 3."
oeis.org/A113558

Me on The Aperiodical: the enormous difficulty of telling the truth about escalators with statistics aperiodical.com/2020/09/the-en

Interactive 3d knot table: prideout.net/knotgl/

One of many interesting visualizations on "the little grasshopper", prideout.net/, by Philip Rideout (author of the svg3d Python library that I linked earlier)

puzzle solution, PostScript source code

@dudeney_puzzles graphics in PS

% A6 paper
<< /PageSize [297 420] >> setpagedevice

/scaling 30 def

/line {
newpath
0 0 moveto
0 1 lineto
stroke
} def

/page-center {
currentpagedevice /PageSize get {
2 div
} forall
} def

page-center translate
scaling scaling scale
1 scaling div setlinewidth
6 {
60 rotate
line
} repeat

6 {
0 1 translate
2 60 mul rotate
line
-2 60 mul rotate
0 -1 translate
60 rotate
} repeat

showpage

Six years after the last one, I've done another Aperiodical Round Up.
Now *that's* aperiodic!
aperiodical.com/2020/08/aperio

I love it when I rediscover an integer sequence with an enormous OEIS entry: oeis.org/A008292

This nonsense brought to you by this nonsense: mathstodon.xyz/@christianp/104

Hello, I'm a postdoctoral researcher at Rikagaku Kenkyusho (RIKEN) (Wako Campus) in the iTHEMS program working in the field of mathematical , data , and . I am a founding member of Math+ and a member of the Solid Modeling Association, Eurographics, SIAM as well as of the SIAM activity group on Geometric Design and the Solid Modeling Association. Furthermore, I am an associate editor of the Journal of Mathematics and the Arts. 🤗

$$R_{\mu\nu} - \frac{1}{2} R g_{\mu\nu} + \Lambda g_{\mu\nu} = \frac{ 8\pi G}{c^4} T_{\mu\nu}$$

I've made a clock which runs through every permutation of a deck of cards, swapping one pair every second.
It's not very useful.
permutation-clock.glitch.me/

Idea: a page which shows a bijection between the first 52! unix timestamps and shuffles of a pack of cards. Once a second, it moves to the next one.

I've made a patch for just this feature at gist.github.com/christianp/629, though it's only really useful in conjunction with the rest of my mathstodon branch, which uses MathJax to render LaTeX in toot content: github.com/christianp/mastodon

mathstodon.xyz now has a live preview and completion of LaTeX!
This has been on my to-do list for a long time. You no longer need to worry if LaTeX will display properly or not.

Poor LaTeX in a closed-access journal

This is pretty dire, from a closed-access journal: these matrices are typeset using \array{cc} environments, but they just used a horizontal space instead of a column separator, so nothing is aligned.