futurebird, to math
@futurebird@sauropods.win avatar

I don't understand how lace is made, but looking at the and pins and patterns ... listen buddy I know math when I see it. This is A Thing. Obviously.

Right away I want to know: Can I encode information in lace?

How much of an expert must one be to make your own patterns?

What about the creation of surfaces?

is more accessible, and people have been exploring math with knitting forever.

But what possibilities does lace offer?

What is the theory of lace?

tatted lace spheres, the threads are starched, these delicate baubles have been used as Christmas ornaments.
More lace ribbons, a simple pattern that contains periodic distortions to the regular grid.
An excerpt from Mathematics Magazine Vol. 91, No. 4 (October 2018), pp. 307-309 Shows I'm hardly the first person to muse about this. Need to get my hands on the rest of this article, obviously. Q: When did it first occur to you that there might be some interesting math behind the lace-making process? VI: It really started when I discovered bobbin lace in my mid-20s. Bobbin lace is complicated, but very logical. It is kind of like doing a Sudoku puzzle. Here, the puzzle is to figure out what threads to braid together and in what order, to find a successful path through the pattern. Q: What does success mean in this context? Does it mean producing a piece that’s aesthetically pleasing or something else? VI: Unlike a pattern for knitting or crochet, a bobbin lace pattern is not expressed as a linear sequence of written steps. A bobbin lace pattern is typically a diagram. There are many possible ways different threads can come together and most of those are not successful, meaning you could end up with too many threads in one area and not Math. Mag. 91 (2018) 307-309. doi : 10. 1080/0025570X . 2018. 1503465 © Mathematical Association of America MSC: Primary 01A70 Allison Henrich (MR Author ID: 900050) Color versionsof one ormore of the figures in the article can be found online at www.tandfonline.com/umma.

eniko, to gamedev
@eniko@peoplemaking.games avatar

The first episode of Coding History: 3D from Mode7 to DOOM is live now! It explains how to rotate points in 2D space and why the rotation formula so often used in game development is the way it is: https://www.youtube.com/watch?v=JC5IMfK7Yfw

Please go check it out and boost this post if you want to support an educational video series about old school 80s and 90s 3D 🙏

futurebird, to math
@futurebird@sauropods.win avatar

I’m making some “fractions sensitivity training” warm up questions for grade five and six. Any particularly silly or subtle suggestions would be a big help. These are too boring.

A. How is 15min like $0.25?
B. How are three cat paws like 45min?
C. How is 12min like holding up one finger on one hand? .. or like $0.20?
D. How is one ant leg like 10 min?
F. How is holding up four fingers on one hand like 48min? … or like 8 dimes?

Ideas?

MichaelPorter, to math
@MichaelPorter@ottawa.place avatar

Mathematicians and math educators only, please. Which is correct?
(Background - Math was my best subject, but it was decades ago, and now that I’m tutoring my niece I run into things like this… This is a genuine request for assistance, not a trap!)

At some point, probably long after I left a math class, I started assuming the square root sign meant both roots. I am now becoming aware that it only means the principal (positive) root, and if you want both roots you have to be explicit.

Comments very welcome.

futurebird, to math
@futurebird@sauropods.win avatar

Every year the many names for mathematical statements cause my students a little anxiety. I want to make an Euler diagram to show how they all overlap and intersect— so please mention any words I could add to this list:

statement
proposition
theorem
axiom
postulate
rule
law
definition
formula
corollary
lemma
conjecture
hypothesis

Can you think of any others?

dmm, to science
@dmm@mathstodon.xyz avatar

Here's a cool integral involving the golden ratio.

My notes are here: https://davidmeyer.github.io/qc/golden_ratio.pdf. The LaTeX source is here: https://www.overleaf.com/read/mkjdjwtmnzjd.

As always, questions/comments/corrections/* greatly appreciated.

ned, (edited ) to random
@ned@mstdn.ca avatar

Okay, so seems that the debate on this is a generational thing. The meme is backwards because it's the older guy who should be saying 1, not the younger women.

Basically, if you were taught older conventions like I was (being an old fart), you would divide the 6 by the product of everything to the right of the division, because you would treat the ÷ as a /, and treat the product as a denominator.

We used to treat ÷ as an easier way to write out a fractional problem but no longer do that.

futurebird, to mathematics
@futurebird@sauropods.win avatar

I tried a new activity this summer. I was worried the shape toys would feel too “baby” — but combined with “build every Johnson Solid We can” (which is hard) it was just about right.

With older kids I’d withhold the images and just tell them how many of each kind of face.

I don’t have a good elementary explanation for why it’s sometimes possible to build an “invalid” solid— would love any suggestions on that.

fractalkitty, to genart
@fractalkitty@mathstodon.xyz avatar

This needs tweaks, but if you want to endlessly add fibonacci numbers...

Is it endless?

What is the average score of randomly moving until you lose?

do you play better when you don't try?

I might bother to answer these, I might not.

https://sumfib.com/

It should work on mobile other than not having a delay when you hit the end. (I need to figure out how to fix that)

grumpygamer, to gamedev
@grumpygamer@mastodon.gamedev.place avatar

If you ask 10 game dev friends to play your game's prototype/alpha, 5 Won't even download it, 3 of those who download it will boot it once and say "looks great, I'll try it this weekend" and never do. 2 will give you feedback, only 1 of those will give you useful feedback. Cheer up, It has nothing to do with how good your game is, it's just math.

mjambon, to statistics
@mjambon@qoto.org avatar

If half of an airline's flights are full and half are empty, passengers will complain that the flights are full every time, contrasting with the assessment of the crew who report that half of the flights are empty. How do you call this effect/paradox? (I forgot)

The same effect explains that if you have an average number of friends (= popularity), more than half of your friends are more popular than you.

Or when your doctor tells you you're in average physical condition but each time you go cycling, most cyclists you come across are faster than you (because the fast cyclists are also the ones who spend the most time on the roads and are encountered disproportionately).

CCochard, to math
@CCochard@mastodon.social avatar

In thermodynamics, why is work not a differential?
I wwould welcome any advice on ressources that explains this.

ai6yr, to math

Holy crap. Someone won the Texas Lotto -- to the tune of $95 million -- by buying every combination of number available. They apparently invested approximately $25.8M to accomplish that. (Paywall busted below) https://archive.is/etkX9

TheQuinbox, to math

What Braille displays (preferably 32 cells or above) would people recommend for use with NVDA? Price doesn't matter, I'm going to get the rehab agency to pay for it because I really need a display for my math, but I can't do it with my current, 14-cell display.

azonenberg, to math
@azonenberg@ioc.exchange avatar

Ok, this one is for the discrete gurus out there.

Let N = CRC32(X)

Given N, is it possible to efficiently calculate CRC32(concat(X, Y)) where Y is a known sized, but very long, sequence of 0xFF bytes?

Obviously you can just seed the CRC with N and iterate, feeding 0xFF in each cycle, but is there any kind of shortcut you can take if you know the input is always a 1 bit?

mina, to math
@mina@berlin.social avatar

Do you like doughnuts or pretzels?

Probably yes. I do. 😋

But did you know that their shapes also matter a great deal in ? Specifically, in an area called ?

1/5

2 delicious pretzels with salt on a blue and white napkin

christianp, to science
@christianp@mathstodon.xyz avatar

You have pieces labelled 1 to N.
You arrange them in a line N times, so that at turn k the piece labelled k is in position k. (so on the first turn piece 1 is at the start, on turn 2 piece 2 is next to that, and so on)
No piece can be in the same position for two consecutive turns.

How many ways of doing this are there?

For N=3, there's only one:
On turn 1, it must be 1xx
On turn 2, it must be x2x and 2 can't be where it was before, so turn 1 was 132 and turn 2 is 321.
On turn 3 it must be 213.

For N=2, it can't be done.

For N=4, there are loads of ways.

Chrishallbeck, to comics
@Chrishallbeck@mastodon.social avatar

Geometrical.

vmbrasseur, to math
@vmbrasseur@social.vmbrasseur.com avatar

Pythagorean Theorem Found On Clay Tablet 1,000 Years Older Than Pythagoras

"The conclusion is inescapable. The Babylonians knew the relation between the length of the diagonal of a square and its side: d=square root of 2," mathematician Bruce Ratner writes in a paper on the topic.

https://www.iflscience.com/pythagorean-theorem-found-on-clay-tablet-1000-years-older-than-pythagoras-72091

ned, (edited ) to Humor
@ned@mstdn.ca avatar
astro_jcm, to physics
@astro_jcm@mastodon.online avatar

Every. Single. Time.

vwbusguy, to mastodon
@vwbusguy@mastodon.online avatar

OK, , I have a problem for you. Explain to me how these calories make sense between Coke, Seven Up, and Dr. Pepper.

DrTCombs, to math
@DrTCombs@transportation.social avatar

Hi people! If you had half an hour a handful of incredibly bright, incredibly bored 10 year olds, what math would you teach them?

The 4th grade math curriculum is letting these kids down, and they are hungry for a challenge...and to see that math can be fun again!

in advance!

thisismyglasgow, to glasgow
@thisismyglasgow@mastodon.scot avatar

There's a teddy bear handing out maths problems in the West End of Glasgow!

fell, (edited ) to programming
@fell@ma.fellr.net avatar

I was experimenting with colour distances at work today. I need to find out how similar two colours are, so I wrote a little test program and it was surprisingly pretty.

The algorithm is simple:

  1. Fill the canvas with random colours.
  2. Set the first pixel (top left) to red.
  3. For all pixels, find the most similar pixel and move it next to the current pixel.

To determine the similarity, I calculated the 3D distance in the RGB, HSV and YUV color spaces, which brought very different results. Now, it's quite possible that my HSV and YUV conversion functions were just broken, but that's okay.

(I recommend zooming in!)

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