(Or, a Cobordism of Carbon.)
Here’s my understanding of this (with the energy cost dip greatly exaggerated).
Oops! It takes a village (down) to raise an (American) child.
Anyone want to make one of these with real numbers?
Update: This is what I call an entry-level metaphor – it’s a rough sketch of the relation between the concepts, not a productive metaphor that can be used to reason about them beyond this. It doesn’t support analytic microeconomic analysis, and it’s not even consistent at the level of the supply chain. (For example, the unit cost needs to include the component cost, whereas the illustration shows these as complementary; this is because the metaphor leaves out profit.) Nonetheless, I find it a helpful starting point before going more analytic.
Here’s something I’ve wanted for a long time. So I finally built it. reAnimator is a tool for visualizing how regular expression engines use finite-state automata to match regular regular expression patterns against text.
This is intended to demonstrate the implementation of regular expressions. If you want to learn how to use them instead, I recommend these references instead:
Recently I reviewed the programming languages I’ve used over the 28 years1 of my programming career. The result is shown in the chart below. (Click on the image to see it full size.)
There are some obvious trends here2. The languages are mostly getting higher level. There are a few “survivors”: languages that I’ve used over the the course of a decade, although discontiguously: C/C++, Common Lisp, and Java. Java has replaced C (except for a stint around 2000 where I went back to low-level graphics programming at Alphamask), and the scripting languages have taken over from Common Lisp — they’re slower, but they’re terse, have better libraries, and are easier to deploy.
Last week I wrote a couple of tools to keep track of subversion checkins:
The Subversion Log Viewer is a master-detail list of recent subversion revisions. It’s based on the OpenLaszlo contactlist example. The nicest feature is really an afterthought: at the last moment, I added faces for authors; I think this makes projects a lot friendlier. Right now it only adds the faces to the OpenLaszlo log; let me know if you’re interested in using this for your own project, and I’ll make a public API for adding faces to a repository.
Expialidocio.us is a tool for visualizing your del.icio.us posting activity. It displays a graph of your posting activity over time. You can select a timespan from this graph, and it will show you a tag cloud weighted by just those dates.
Expialidocio.us was inspired by a posting by Jon Udell. Coming full circle, Udell has posted since posted about this application.
“Aargh!” But how do you spell it?
(Click here to skip straight to the visualization.)
In the late nineties, I tried using internet search as a spelling corrector. (I think I was using AltaVista at the time. It was the latest and greatest search engine, supplanting — was it Lycos?)
At the time, for the words I tried, there were about two orders of magnitude between a misspelling and the correct word. A spelling variant, such as “color” and “colour”, were typically less than one order of magnitude.
PackageMapper shows you a map of your FedEx, UPS, USPS package routes. Enter a carrier and a tracking number to see your package’s progress plotted on the map. Sign in to enter a list of packages and see their current locations on a table or map.
This is an itch I’ve wanted to scratch for about a year now: being able to see where all my packages are on a map. On Thanksgiving morning I discovered SimpleTracking.com, which gives you an RSS feed for a UPS or USPS package. Over Thanksgiving weekend I added FedEx and mashed it up with Google Maps, and this is the result.
I posed a second-grader the question of what nine squared was. She reasoned that ten squared is 100, and nine times ten is ten less then that, and nine times nine is nine less than that, so the answer is 81. Then I asked her what eight squared was, and she was flummoxed. She saw that it was a similar problem to the one she’d just solved, but wasn’t sure how to apply the analogy.
Here are the pictures that showed her how to figure out the answer. We drew the location of the squares on a multiplication grid:
and I introduced the idea of a “solution structure”. A solution structure is a graphical representation of the steps of a solution. This is the section that represents the relation between 92 and 102.
Last weekend, I shared some interesting properties of numbers with my kids.
The great thing about explaining something to a non-expert is that you have to actually understand the topic. (This is why making teaching universities and research universities the same actually makes sense.) If you hide behind a formalism, the explanation won’t work. Usually, this means that you didn’t understand why the formalism worked either.
This is why I thought “why are far away things smaller?” was such a great question. “Similar triangles” answers are brittle, and if a tiny error makes far away things come out bigger instead, you won’t catch yourself until you got to the end of the proof.