So, my wife and daughter were taking some squares of fabric to make a 3×3 quilt for a doll that’s going in an Operation Christmas Child shoebox. My wife asked me if it were possible, using 3 of each square, to not have any repeats in any row or column, and not to have a diagonal that’s solid. In short, the answer is no. Continue reading 3×3 Quilt: n-Tile n×n checkerboards

# Author: petercj@pryrt.com

## Reuleaux Triangles (Generalized) — Triangles with ZoomZoom

I’m a fan of a nice rounded triangle: the Wankel-based rotary engines found in the Mazda RX-7 and RX-8 use a rounded triangle, and I’ve owned one of each. And there’s the mathematically more pure Reuleaux triangle, which is a curve of constant width, which gives it some nice mathematical properties.

Continue reading Reuleaux Triangles (Generalized) — Triangles with ZoomZoom

## Hello Kitty Takes A Trip

Reading to my daughter, my mind sometimes goes on tangents from the story. In Hello Kitty Takes A Trip, the titular character goes on a trip to the USA with some friends (and without her parents; based on behavior, she’s quite the mix of very young and very old). But, within the US, she jumps back and forth to some rather geographically-diverse locations: New York to Nantucket to Florida to Vermont to Hawaii. My tangent as I read this story: wondering as to whether the authors realize the enormous distances involved in such “quick jaunts”.

Knowing that Hello Kitty is supposedly a girl in England, but is Japanese in origin, I decided to use our old trusty globe to get a sense of the distances involved, and try to transpose it into a European vacation and an Asian vacation.

Getting out a piece of string and a ruler, and enlisting my daughter’s help at recording the information in a notebook (got to teach her good scientific data-gathering procedures, after all), I set to work. Her data: “1cm 4.5cm 5cm 19cm”. My additions: 2cm = 500mi, for reference: so about 250mi from NY to Nantucket, 1125mi from Nantucket to Florida (I picked Miami as a likely destination, since she mentioned a beach but not a theme park), 1250mi from Florida to Vermont, and 4750mi from Vermont to Hawaii. (Google and distance.to confirm my distances to within about 10%.)

So, then I took the string, and those same distances on the globe, and moved to Europe. I wanted to attempt vaguely similar climates, etc. So in Europe, I found that her trip could be approximated by starting in Amsterdam, flying to Copenhagen, then to Sicily, then to Lithuania, then to Bermuda or northern Madagascar. In Asia, she could go from Tokyo to Osaka, to Taiwan, to Beijing, then finally to the Solomon Islands (with stretch miles, she could’ve made it to Hawaii from Beijing).

Or, if she had started in New York, and just wanted the equivalent distance she had traveled through the US, she could have made a direct great-circle flight to Pakistan, or Samoa, or Shanghai.

So, that just puts into perspective how amazing Hello Kitty’s trip was.

(Thanks to http://www.distance.to/ for confirmations on distances and the final explorations to Pakistan, Samoa, and Shanghai from New York.)

## π Day

π id one of my favorite numbers (e^{iπ}=0-1 show my favorite numbers, in no order of preference), so you’d think that I’d be a huge fan of π day — but I’m not.

## pluto-charon for binary planet

In my Dec 3 facebook post of me next to the Pluto-discovering telescope at Lowell Observatory, I hashtagged #PlutoCharonForBinaryPlanet. While facebook finds no other instances of that exact hashtag, the concept isn’t new.

## about geekydad

I’m a geek, an engineer, and a dad. These pages are some of the things that come about because of one or more of those attributes. 🙂

I changed from “geek dad” to “geeky dad” for these subpages; turns out, there’s already an awesome GeekDad.com blog, which I don’t want name-confusion with. There’s a geekydad.net, but it hasn’t been active for more than a year, so I won’t bother avoiding name-confusion. Especially since I’m not trying for the domain name, just a header for these pages. 🙂

My wife homeschools our children, and she does the teaching. Sometimes she waits for Saturday morning to do the science experiments, so I can participate. And sometimes, because of a kids book they’ve read, or an idea I’ve had, I get to teach them some mathematical or scientific principal, or I come up with an experiment or demonstration (depending on the complexity or danger levels – sometimes, I get a bit too mythbustery for them to safely help).

sometimes, I just think about odd science or technology. My wife has caught me multiple times using my kids’ magna doodle, whiteboard, or chalkboard to work out some physics or stoichiometric equations … and that’s just what she’s noticed. 🙂

## converting to automated blog

I’ve given in to the dark side: I have converted the blog-like portion of my site to blog software. Spending so much time with raw HTML, rather than on the content of the posts, was getting old and tedious. I watched with jealousy as my wife quickly got her new structure for joneschristy.com up and running, and looking great (though it was fun for me to get the various plugins installed to help her automate some of the stuff I watched her do manually, even in the tool).

Since I’ve been able to make most of my nifty features (AsciiMathML equations and MathJax graphs) work embedded, it seems silly not to convert. I’ve started moving my old entries over to the new tool, but it will take some time to move them all. In the meantime, I’ve moved the old static-HTML page URLs from /geekydad/ over to /extrageeky/.

## ripple

Some time ago, I tried coming up with my own water-drop/ripple simulation for making a small animated-gif background (akin to the moving backgrounds, like clouds, ocean breakers, etc, that are so popular as church lyric-projector backgrounds right now). Basically, I had a sinusoidish curve, decaying with radius and time; I simulated a dozen or so of these drips, usually centered off-picture, and added the curves; it made for some nice randomish moving water-surface. (Sorry, I cannot find where I put it for now.)

## PseuDoKu

“PseuDoKu” = What I’m calling variants of sudoku, whether simplificiation of or extrapolation from the original.

My daughter enjoys playing the “number game” on my phone with me; I tell her where to put the next solved number (“put a 2 between the 5 and the 6 in that grey box”, etc.). I’ve thus started doing simpler grids on the chalkboard — with just a 4×4 grid, and one number missing from each row or column, and haven’t made the logic require one-of-each-per-2×2. The other day, she asked for “1 to 5” instead of “1 to 4”: since I haven’t introduced her to the boxes, the fact that 5×5 cannot have the sub-box regions is irrelevant.

## PseuDoKu Details

What I’m calling variants of sudoku, whether simplificiation of or extrapolation from the original.

My daughter enjoys playing the “number game” on my phone with me; I tell her where to put the next solved number (“put a 2 between the 5 and the 6 in that grey box”, etc.). I’ve thus started doing simpler grids on the chalkboard — with just a 4×4 grid, and one number missing from each row or column, and haven’t made the logic require one-of-each-per-2×2. The other day, she asked for “1-5” instead of “1-4”: since I haven’t introduced her to the boxes, the fact that 5×5 cannot have the sub-boxes is irrelevant.