`\pi` Day 2020 Art — Digits, poetically.
On March 14th celebrate `\pi` Day. Hug `\pi`—find a way to do it.
For those who favour `\tau=2\pi` will have to postpone celebrations until July 26th. That's what you get for thinking that `\pi` is wrong. I sympathize with this position and have `\tau` day art too!
If you're not into details, you may opt to party on July 22nd, which is `\pi` approximation day (`\pi` ≈ 22/7). It's 20% more accurate that the official `\pi` day!
Finally, if you believe that `\pi = 3`, you should read why `\pi` is not equal to 3.
Welcome to this year's celebration of `\pi` and mathematics. Among the chaos of COVID-19, this year `\pi` Day celebrations are short poetic emissions I call “piku”. They are brief pauses for the time.
Start by reading how piku are constructed and then browse submitted piku. Consider participating by submitting your own piku. All you need is a pen and a few (small) words. Very therapeutic.
But if the words here don't help, immerse yourself in my coronavirus art. It's quite catching.
If you enjoy poetry and words, see how I convert spam into poems in the style of ee cummings and if you like to see words arrange on page, look through my typographic art.
You may know the haiku (俳句) as a short three line poem whose lines traditionally have 5, 7 and 5 syllables (specifically, morae or phonetic sounds).
On a recent trip to Japan I was looking to my environment for inspiration for this year's `\pi` Day. I also really wanted a scheme that would allow people to contribute to the art so that everyone could be both a participant and an audience.
After scribbling for a little bit (or a long while), I came up with the idea of a piku (`\pi`ku, パイク). Analogously to a haiku, the piku is poem whose structure is constrained. But in this case, the constraints are the digits of `\pi` itself.
The piku
The simplest piku is a 3 phrase poem with 3, 1 and 4 syllables, respectively. Perhaps the most trivial piku is just the list of digits.
Specifically, Haiku count the number of phonetic sounds which isn't always the same as syllables. For example, the word "any" has two such sounds: a-ny.
If you're interested in how the counting of sounds is done in Japanese, read about marking time and beats in Haiku.
But a more fun one would be
Longer words can be used, of course. But watch out for the lines that require a single syllable.
You can use hyphenation to work around the syllable count.
plural of piku is piku
Piku is singulare tantum—its plural form is the same as its singular.
This is because its inspiration is the haiku and in Japanese nouns do not have different singular and plural forms,
Longer piku
In general, a piku may have more than 3 lines. This reflects the fact that the digits of `\pi` do not terminate.
The endless piku is just waiting to be written. Well... started, at least.
Handling zeros
The digit zero is a line with no syllables and corresponds to a compulsory verse break. But because the first zero in `\pi` is at digit 33, you wouldn't see a verse break for a while.
Therefore, you're free to introduce a verse break anywhere in the piku (this does not use up a digit). For example,
Generalizing the piku — the nku
Any number, `n`, has its own nku. The rules for its construction are the same: each digit generates a line with corresponding number of syllables.
For example, the haiku is an nku for `n = 575`.
The year of your birth has an nku—you might want to try composing one to reflect on your origins.
In fact, any date (e.g. DDMMYYYY) can be made into an nku. This year's `\pi` date in this format is 14032020 and here's one possible nku.
The trailing zero in the number creates a verse break at the end of a poem. This can be ignored or used to generate a blank line if the poem is set with other text on the page.
Nature Biotechnology cover
My cover design on the 7 April 2026 Nature Biotechnology issue shows the dendrogram that represents a cluster of uniquely expressed (or downregulated) genes in human naive stem cells induced from such cells. Within each dendrogram block, the genomic barcode sequence (sampled from Supplementary Table 1) is depicted with a Code 39 barcode. The highlighted barcode is one of those used for cell isolation.
Ishiguro S. et al. A multi-kingdom genetic barcoding system for precise clone isolation (2026) Nature Biotechnology 44:616–629.
Browse my gallery of cover designs.
Happy 2026 π Day—
Art for the 5%
Celebrate π Day (March 14th) and enjoy the art — but only if you're part of the 5%.
Go ahead, see what you can't see.
Ishihara's Tests for Colour Deficiency
Authentic and accurate images of Ishihara's test plates photographed (and lovingly color-corrected) from the 38-plate Ishihara's Tests for Colour Deficiency.
I also provide the position, size, and color of each circle on each test plate.
Symmetric alternatives to the ordinary least squares regression
What immortal hand or eye, could frame thy fearful symmetry? — William Blake, "The Tyger"
This month, we look at symmetric regression, which, unlike simple linear regression, it is reversible — remaining unaltered when the variables are swapped.
Simple linear regression can summarize the linear relationship between two variables `X` and `Y` — for example, when `Y` is considered the response (dependent) and `X` the predictor (independent) variable.
However, there are times when we are not interested (or able) to distinguish between dependent and independent variables — either because they have the same importance or the same role. This is where symmetric regression can help.
Luca Greco, George Luta, Martin Krzywinski & Naomi Altman (2025) Points of significance: Symmetric alternatives to the ordinary least squares regression. Nat. Methods 22:1610–1612.
Beyond Belief Campaign BRCA Art
Fuelled by philanthropy, findings into the workings of BRCA1 and BRCA2 genes have led to groundbreaking research and lifesaving innovations to care for families facing cancer.
This set of 100 one-of-a-kind prints explore the structure of these genes. Each artwork is unique — if you put them all together, you get the full sequence of the BRCA1 and BRCA2 proteins.
Propensity score weighting
The needs of the many outweigh the needs of the few. —Mr. Spock (Star Trek II)
This month, we explore a related and powerful technique to address bias: propensity score weighting (PSW), which applies weights to each subject instead of matching (or discarding) them.
Kurz, C.F., Krzywinski, M. & Altman, N. (2025) Points of significance: Propensity score weighting. Nat. Methods 22:638–640.