Which shape of sheet the flaps want
sheet-shape is one function. Everything below was drawn by it when the site was
last published, at settings taken from the essays rather than invented for this page — so a figure
here is the same figure a reader meets in an essay, and when the generator changes, this
page changes with it.
With nothing specified
n: 7, view: "sweep"
view: "pair", n: 6, aspects: [1, 1.2, 1.4142135623730951, 1.6, 1.8, 2, 2.5, 3], show: [1, 1.4142135623730951]
n: 7, aspects: [1, 1.5, 2, 2.5, 3.5, 5, 7], restarts: 80, steps: 5000, view: "sweep"
What it checked while it drew
Collected while it drew, not written by hand. The count is how many separate times that claim was put to the test.
- for 7 flaps a sheet of 1.8 to 1 uses 72.2% of its area against the square's 66.8% ×5
- 8 sheet shapes are measured against the square, which the sweep contains ×2
- for 9 flaps no sheet shape in the sweep beats the square, which uses 78.5% of its area ×1
Where it is called
Every figure listed here is drawn by the same rule, so a mistake in the rule would be in all of them at once, and so would a correction.
One member of a family
A4 halves into A5 and keeps its shape, which is the one thing everybody knows about paper sizes. The property is not about halving and not about two: a rectangle in the ratio √n divides into n copies of itself, for every n, and every one of those rectangles can be folded out of a square one diagonal at a time.
The rectangle that keeps its shape
Halving a rectangle across its long side turns a proportion of r into one of 2/r, so almost every sheet comes out of the fold a different shape from the one that went in. Exactly one does not, and it is not a shape anybody chose.
The square is a choice
Every packing on this site has been into a square, because origami paper is sold square. Hold the area fixed and vary the shape instead and the efficiency turns out to be spiky rather than smooth — with the same peak value at every proportion that is a ratio of two factors of the flap count, and nowhere else.
All the figures · The designing a base field · The patterns a reader can fold