Fungible Fractals

Thinking it over, I’ve decided that trircle is a much better name than ciangle:

A Sierpiński triangle

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A Sierpiński trircle, or triangle converted into a circle


A trircle is a triangle converted into a circle; a ciangle is a circle converted into a triangle. Or another regular polygon. The trircle reminded me that circularized fractals are fungible, because the Sierpiński triangle can be converted into another regular polygon like a square or pentagon or hexagon. You can go viâ the trircle, but you don’t have to. The point is that the Sierpiński triangle has a center and points lying at some distance and some angle 0° through 360°, so you can easily adjust the points to fit inside any other regular polygon:

A Sierpiński triangle again

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A Sierpiński trare, or triangle converted into square

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A Sierpiński trentagon

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A Sierpiński trexagon

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A Sierpiński treptagon

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A Sierpiński troctogon


Here’s an animation of the conversions:

Sierpiński triangle → square, pentagon, hexagon, heptagon, octagon (animated at ezGif)


A Sierpiński carpet, with points lying at 0° through 360° inside a square, is similarly fungible:

A Sierpiński carpet

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A Sierpiński carpet converted into a circle

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A Sierpiński carpet converted into a triangle

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A Sierpiński carpet again

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A Sierpiński carpet converted into a pentagon

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And an animation of the carpet conversions:

Sierpiński carpet → triangle, pentagon, hexagon, heptagon, octagon (animated at ezGif)


Finally, and fungibly, the fractal that I call the centered Sierpiński triangle:

A centered Sierpiński triangle

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A centered Sierpiński trircle, or triangle converted into a circle

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And the final animation:

Centered Sierpiński triangle → square, pentagon, hexagon, heptagon, octagon (animated at ezGif)


Squaring the Triangle

It’s an interesting little exercise in elementary trigonometry to turn the Sierpiński triangle…

A Sierpiński triangle


…into its circular equivalent:

A Sierpiński trisc


You could call that a trisc, because it’s a triangle turned into a disc. And here’s triangle-and-trisc in one image:

Sierpiński triangle + Sierpiński trisc


But what’s the square equivalent of a Sierpiński triangle? This is:

Square from Sierpiński triangle


You can do that directly, as it were:

Sierpiński triangle → square


Or you can convert the triangle into a disc, then the disc into a square, like this:

Sierpiński triangle → trisc → square


Now try converting the triangle into a pentagon:

Pentagon from Sierpiński triangle


Sierpiński triangle → pentagon


Sierpiński triangle → trisc → pentagon


And a hexagon:

Hexagon from Sierpiński triangle


Sierpiński triangle → hexagon


Sierpiński triangle → trisc → hexagon


But you can also convert the Sierpiński trisc back into a Sierpiński triangle, then into a Sierpiński trisc again:

Sierpiński triangle → trisc → triangle → trisc


Sierpiński triangle → trisc → triangle → trisc (animated at Ezgif)


Sierpiński triangle → trisc → triangle → trisc (b&w)


Sierpiński triangle → trisc → triangle → trisc (b&w) (animated at Ezgif)


After triangles come squares. Here’s a shape called a T-square fractal:

T-square fractal


And here’s the circular equivalent of a T-square fractal:

T-square fractal → T-squisc


T-square fractal + T-squisc


If a disc from a triangle is a trisc, then a disc from a square is a squisc (it would be pentisc, hexisc, heptisc for pentagonal, hexagonal and heptagonal fractals). Here’s the octagonal equivalent of a T-square fractal:

Octagon from T-square fractal


As with the Sierpiński trisc, you can use the T-squisc to create the T-octagon:

T-square fractal → T-squisc → T-octagon (color)


Or you can convert the T-square directly into the T-octagon:

T-square fractal to T-octagon fractal

But using the squisc makes for interesting multiple images:


T-square fractal → T-squisc → T-octagon (b&w)


T-square fractal → T-squisc → T-octagon → T-squisc


T-square fractal → T-squisc → T-octagon → T-squisc (animated at Ezgif)


The conversions from polygon to polygon look best when the number of sides in the higher polygon are a multiple of the number of sides in the lower, like this:

Sierpiński triangle → Sierpiński hexagon → Sierpiński nonagon