Andrew Stacey

@mathforge

Mathematician: formerly academic (differential topology), currently educational (Head of Department in a UK secondary school). Side interests in Maths & Programming & Art. Website:

452 Folgt1.755 Follower2.885 Posts

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Andrew Stacey@mathforge· 6d

Well, I had to ask, didn't I? Pros: it's smooth, without being overly analytic. Although individual support is guarded [bounded], taken together, it's total. Cons: can be a bit derivative, and while many norms are accepted, they rapidly decrease after a bit. Felt a bit dark [Schwartz]. #mathsky

A poster on the side of an old-fashioned English pub saying "Ask us sbout our function space"

Below that, it says "Available for all occasions" and then "Please speak to a member of the team for more info"

Andrew Stacey@mathforge· 29d

Proof that the vikings got as far as Japan.

A label on a pack of origami paper from Hobbycraft. The label reads "Creativity the Scandinavian way".

The rest of the label contains samples of the paper: all are greyscale with patterns on both sides, most patterns are based on a simple geometric design with one more floral and one based on handwriting.

The pack contains 50 assorted sheets, 80g, and 10×10cm.

Andrew Stacey@mathforge· Jun 2

Raising a glass to Richmal Crompton and Matryn Jarvis. (No reason, other than the drink reminded me of listening to him reading her stories)

A glass of what might be mistaken to be whiskey, but is actually a cold brew liquorice tea - which might be called "liquorice water", much beloved by William Brown of the Just William stories.

Andrew Stacey@mathforge· Jun 2

Wanted to see how much @chadtopaz.bsky.social 's new book costs. Intrigued by the prospect of a sale from the publishers. Not too sure the discount is really offering much, here. #CoreMaths

A screenshot from the Princeton University Press website advertising a discount. Only the actual amount is obscured by a weird icon so it reads "0% off most titles, May 4 to June 9"

Andrew Stacey@mathforge· May 26

Magic roundabouts seem to be appearing everywhere these days. I drove round this one in Hemel Hempstead earlier today. The red lines of traffic are simply people trying to figure out which way round it to drive.

Screenshot of google maps showing a "magic roundabout" in Hemel Hempstead with six mini roundabouts. The traffic colours are showing most routes in red.

Andrew Stacey@mathforge· May 3

'Yet a sensitive heart the rhinoceros owns, If you doubt it here's the proof: That thing on his nose is for getting stones Out of a horse's hoof. He seldom - if ever - meets a horse (It is this that makes him sad) When he does then it hasn't a stone in its hoof But he would if he did and it had!

A baby rhinoceros next to an adult rhino, both facing towards the camera.

Andrew Stacey@mathforge· May 3

'Oh, nobody likes the rhinoceros much If you ask the reason why They will say because of his scaly touch Or his hard, unflattering eye. But should you ask a truthful man You will get this quick response: "I do not trust that thing on his nose - The bodger on his bonce!" #Cotswolds

Two rhinoceroses (rhonoceri?) at Cotswolds Wildlife Park, facing each other with the shape of their heads and horns making a lovely parabola.

Andrew Stacey@mathforge· Mar 2

notes.mathforge.org/notes/publis... #geometrypuzzle #UKMathsChat #mathsky

An arrangement of seven squares. Six of the squares are identical and are arranged so that reading from left to right they form three stacks that abut and are of heights 2,3,1, with each base square aligned with the second square in the stack to its left.

A tilted larger square overlays the six and shares a vertex with the lower right vertex of the bottom-most square. The top left vertex of the uppermost of the six squares lies on an edge of the larger square.

A line is drawn from the left-hand vertex of the larger square to the lower right vertex of the rightmost small square.

The angle formed by this line and the left-hand edge of the larger square is marked with a question mark.

Andrew Stacey@mathforge· Feb 25

Now *that's* not confusing at all! @vmnalex.bsky.social (Admittedly, both notations are correct, but it's a clear example of the point that notationis insufficient) #UKMathsChat #ALevelMaths

An except from the UK government a level maths specification showing the notation for ordered pairs, (x,y), and for open intervals, (a,b).

Between them are notations for closed and half-open intervals.

Andrew Stacey@mathforge· Feb 9

Had a go at the great-granny knot in TikZ, @cubesart.bsky.social

A great-granny knot, consisting of a trefoil where each outer lobe is again a trefoil.

Andrew Stacey@mathforge· Feb 6

Made a stab at explaining intersecting planes in Y12 Further Maths, wasn't sure it was all that clear, then turned round to see that my students had made their own version. #MathsToday

Three pieces of paper, interlocking to illustrate three intersecting planes. The pieces of paper were cut so that they could pass through each other.

Andrew Stacey@mathforge· Jan 24

But the trolls in Norway are so friendly now, and hardly ever eat people. Even if they got trip-trapity over their rickety-rackety bridge.

A tree in a Norwegian forest with a face painted on it consisting of two eyes and a smiley mouth.

Andrew Stacey@mathforge· Jan 20

Trying to figure out which LaTeX package this is from.

Graffiti on a fence in Oxford which reads "Nice One" in large letters. What makes it notable is that the graffiti artist has taken the time to add serifs and other font niceties.

Andrew Stacey@mathforge· Dec 21

Buying hot dogs today. The prices per 100g on the signs are a bit blurred, they were 27.7p per 100g for the jar of 12 and 43.4p per 100g for the jar of 6. After staring at them for some time, and using a calculator to double check, I did buy the jar of 12 as it was the cheaper option. #UKMathsChat

A photo of different sizes of jars of hot dogs, from the Iceland supermarket in the UK.

The jar with 12 hot dogs costs £2.85 and the label says it is 27.7p per 100g.
The jar with 6 hot dogs costs £1.50 and the label says it is 43.5p per 100g.

Also relevant are the weights. The jar of 12 weighs 1030g net, and 720g drained. The jar of 6 is 345g net and 180g drained.

Andrew Stacey@mathforge· Dec 14

Waterstones in Oxford has recently moved across town (nearer the Westgate, further from Blackwell's - which they now own). Some things didn't change in the move. They still stock Good Books. Strong recommend for Christmas.

A book display in Waterstones bookstore in Oxford showing science books including "The Mathematician's Library" by Tom Briggs

Andrew Stacey@mathforge· Dec 2

@catrionaagg.bsky.social the image didn't show in preview

Three squares side by side with a fourth that shares a corner with the right-hand most and passes through the corners shared by the left and middle. The extremes of the tilted and left squares are joined, to form an angle.

Andrew Stacey@mathforge· Nov 18

Here you go!

$A circular braid on six strands, rendered with yellow strand colour on a black background. The braid word is: a_3^{-1} a_2^{-1} a_4 a_2 a_4 a_3 a_1 a_1^{-1} a_3^{-1} a_5^{-1} a_3 a_2^{-1}$

Andrew Stacey@mathforge· Oct 26

I even found a copy in that intellectual backwater that is Cambridge . @teakayb.mathstodon.xyz.ap.brid.gy

A display in Heffers bookstore in Cambridge with "the mathematician's library" in amongst other popular science books.

Andrew Stacey@mathforge· Oct 22

They say that if you stay long enough in the Norrington Room then every author in the country will come and sign your book. Spotted in Oxford's unique bookshop - @teakayb.mathsy.space

A photo of books lying on a shelf in the Norrington Room in Blackwell's bookshop in Oxford. Visible is "The Mathematician's Library" with two other bookish books.

A photo of books on display in the Norrington Room in Blackwell's bookshop in Oxford. Visible is "The Mathematician's Library" in the centre of the display with many other books around it.

Andrew Stacey@mathforge· Oct 14

Oh dear! #ALevelMaths #UKMathsChat #ITeachMaths #mathsky

Text from an a level textbook defining the Maclaurin series of a function f(x) and saying that the series is valid provided that all derivatives have finite values at 0. The claim is that this converges to f(x).

Andrew Stacey@mathforge· Oct 1

#TikZfun

A blue path and a red path, both sine waves and slightly offset horizontally. The paths a split so that the appear to twist around each other. They are rendered with a pen effect so that the line thickness varies as if drawn with a calligraphic pen.

Andrew Stacey@mathforge· Aug 26

Feels more like a channel 4 program than bbc, but good to see that the water companies are trying different things to clean up their pipes.

A headline from the BBC website, advertising a program on iplayer, that reads "Which aspiring sewer will measure up to impress the judges?"

Andrew Stacey@mathforge· Aug 21

"What the tumbledryer hath bound together, let not man put apart."

Cords from clothing that have been twisted and intertwined after being in the tumbledryer.

Andrew Stacey@mathforge· Aug 5

I have a query about one of @catrionaagg.bsky.social 's puzzles. The goal is the area of the red quarter circle. I have a solution that *doesn't* use the semi-circle. Am I missing something, or is that semi-circle irrelevant? #geometrypuzzles notes.mathforge.org/notes/publis...

A right angled triangle with a filled red quarter circle with centre at the right angle and which is tangential to the hypotenuse. The hypotenuse is divided into three equal parts, each labelled "2". The point of tangency of the quarter circle is at a division point, with one part above and two parts below.

Also in the diagram is a semi-circle which has centre on one of the non-hypotenuse sides and which meets tangentially the hypotenuse at the other division point.

Andrew Stacey@mathforge· Aug 4

For some reason, linking directly to an image doesn't fetch a preview of that image. That's annoying. Anyway, here's the image for that puzzle. #mathsky #geometrypuzzles

One of Catriona Agg's puzzles. It consists of four equal-sized squares aligned horizontally with four equilateral triangles on top - one triangle per square - and of the same side length as the squares. These are contained within a semi-circle so that the squares sit on the base of the semi-circle and the arc just touches the tops of the outer two equilateral triangles. The diameter of the semi-circle has length 4.

Andrew Stacey@mathforge· Jul 28

To which I'll add another bat, this one made from quadratics. loopspace.mathforge.org/CountingOnMy...

Andrew Stacey@mathforge· Jul 25

There's also code.mathforge.org/axes/ It puts the numbers at the lines, not in the gaps, and the axes labels are at the ends, not the middles. I should also make it so that you can hyperlink to a set of configurations ...

Axes with horizontal from 0 to 24, labelled "Days", and vertical from 0 to 6, labelled "Workers".

Andrew Stacey@mathforge· Jul 13

This took the combined mental effort of two Oxford graduates and one Cambridge undergraduate to figure out how to remove the base from the rest of the pen. It's designed to be filled with water for painting with watercolours. #mathsky #UKMathsChat #ITeachMaths

A water-fillable pen (for painting with watercolours). The body of the pen can be removed to fill with water.

However, it is reverse-threaded. Something that took us a long time to spot.

Andrew Stacey@mathforge· Jul 10

$Rendering of "3<=4" where the less-than-or-equal sign has a slanted extra line instead of the more common horizontal one. As a bonus for reading the alt-text, the LaTeX command for this is \leqslant.$

Andrew Stacey@mathforge· Jul 1

Anyone know what entity ͏ is? The BBC seems quite keen on it.