Friday  21 Mar 2025           2 comments

How does a program organize a map to facilitate finding the nearest restaurant or gas station or Uber car? One way is to partition the earth's surface into grid cells, which enables a graph search (check the cell you're in, its neighbors, neighbors of neighbors, ...). A flat surface lends itself to being partitioned into a grid of square cells, but what about a sphere?

Uber wrote code to partition the globe into mostly hexagonal cells, where mostly means twelve pentagonal cells and all the rest hexagonal: like a soccer ball, but with a lot more hexagons. Such a grid has a roughly uniform cell-to-cell distance everywhere on Earth. The twelve pentagons are at the vertices of a regular icosahedron. Uber followed an example from R. B. Fuller that orients the icosahedron such that the twelve vertices lie in bodies of water.

Uber has shared source code for their grid system on Github. It's hierarchical: it supports a range of coarse to fine grids. An overview is here and an interactive page showing their grids on a world map is here. Below: a screenshot showing my (rectangular) house and a hexagonal grid cell. My architect neighbor Brian didn't like pentagons. He thought it should be possible to partition a spherical surface with only hexagonal cells. I showed him a proof that it was impossible but he didn't want to believe it.

Wednesday  19 Mar 2025           comment?

We didn't get much precip this winter and it's not looking like we'll get a lot of flower action this spring. A neighbor's Joshua tree is, nonetheless, getting its flower on.

Happy nineteenth, everyone.

Saturday  08 Mar 2025           1 comment

from Classification theory and the number of non‑isomorphic models
by Saharon Shelah.

Tuesday  04 Mar 2025           comment?

One of several satirical floats in a parade in Germany yesterday. Many people commenting on news coverage thought such politically-themed displays were out of place at a traditional yearly carnival. We could use demonstrations like this in Washington though.

Monday  03 Mar 2025           comment?

The bald eagle pair whose live video stream I've occasionally watched over the past few years have three eggs this year, two of which have recently pipped (started to hatch).

From a web page summarizing recent goings-on at the nest:

Pip1 confirmed 3/2 15:09. (We have no way of knowing which egg has pipped. They are laid without numbers.)
Pip2 confirmed 3/3 7:59:45

Wednesday  26 Feb 2025           comment?

I like making things with curved surfaces. Curves offer degrees of freedom that lines and planes don't. With that freedom comes the challenge of designing a shape that you like. Sometimes I write a program to generate dozens of curves with randomly-tweaked parameters for me to pick from.

Sigma recently introduced a camera whose body is CNC‑machined from a solid block of aluminum in a process that takes seven hours. With that much time on that kind of machinery, Sigma could've had pretty much any shape they wanted. It could've been a subtly curved slab reminiscent of an ocean wave. It could've had an intricate, randomized texture. Instead it looks like this:

Sigma named the camera BF which stands for beautiful foolishness and is a reference to a passage from The Book of Tea:

Let us dream of evanescence, and linger in the beautiful foolishness of things.

Monday  24 Feb 2025           comment?

I like having a pendulum clock on my wall. I enjoy winding it once a week.

And as I have to not eat for an hour after taking one medicine, an hourglass is not just a decoration but is also a useful tool.

Monday  17 Feb 2025           1 comment

Friday  14 Feb 2025           comment?

I've been getting email intended for a member of Congress representing a district in New York state. A dopey web site lists one of my email addresses in error as a contact address for him (and ignores my requests to stop).

I get impassioned pleas asking the Representative to oppose the madness coming out of the White House. The most recent one was from a doctor who wanted funding for the NIH to continue.

I write back to everyone, telling them I share their concerns but I'm not the Tom they were trying to contact.

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One of my climbing buddies works as a ranger for the US Forest Service. He patrols the trail to Mt. Whitney. He likes the work. I write this in present tense because it's hard to accept that he was fired this week as part of the Tr‑‑p administration's willy‑nilly decimation of the federal workforce.

In texting me this morning to give me the news, he said, "I'm pretty livid, but in a weird calm angry sort of way."

Saturday  08 Feb 2025           comment?

I broke this blog's comment system when I made some changes to this blog's behind-the-scenes code. Sorry about that. It didn't accept comments earlier today but it's working again now.

Thursday  06 Feb 2025           comment?

These words from four years ago

There's enough going on to warrant posting about politics every day but for a bunch of reasons I'm largely leaving that to other people. Although I may not comment about every dismal bit of news, we are still well and truly fucked.

still apply, although I understated how bad things were.

I'd post pics of jackrabbits (not that doing so would change the world) but they haven't been gracing my yard lately.