Monday, May 26, 2008

Take [the nerd] out to the ball game

Take [the nerd] out to the ball game

My mother-in-law, my wife, my five-year-old twins, and I went to our first St. Paul Saints game last night. Cue the reminiscing and the tenuous connection to geocaching...

I made the varsity baseball team at my high school as a sophomore. That was a big deal at the time, but anyone who has played baseball knows that the young folks on the team get hazed -- carrying all the equipment, stupid nicknames, emotional and physical abuse, all that fun team-building stuff.

I hit a grand-slam home run in my first varsity at-bat, but it was a humiliating experience, because the seniors had nicknamed me "E=MC^2" and were chanting it on my trip around the bases -- I sprinted around to get it over with as quickly as possible. They were yelling "Look at that TRAJECTORY!" and "Calculate the INITIAL VELOCITY!"

Between then and my second at-bat, I wondered if it was really possible for me to hit a home run every time to the plate for my entire career. So the next time to the plate, I uppercut the first two pitches... 0-2. On the third pitch I hit a weak pop-up to the pitcher, and my coach at third base yelled, so that everyone could hear, "Jesus Christ, Bryan, you're not going to hit a home run every time!" The chanting resumed. MC^2! MC^2!


When I was in college, our dream road trip was to visit all 26 (at that time) major league ball parks, and the list expanded to include all minor league ball parks. Now if that kind of road trip could be combined with geocaching...

Saturday, May 24, 2008

GPS, linear algebra, and fractals in computer graphics

Fellow math guy Bunganator called to my attention this article about the linear algebra that is used by the Global Positioning System to determine location.

My puzzle cache Where's Yoda? is a simplified version of this -- think of the data from each guess in the Yoda game as the input from one satellite. Finding Yoda's location amounts to solving the system of equations that results from the information given by each guess.

The article Bunganator sent includes a reference to a book called Linear Algebra, Geodesy, and GPS by Gilbert Strang and Kai Borre. I'll have to check this book out -- I've wondered how to incorporate GPS topics into my courses (rather than the other way 'round... Gah!) -- but I note that the first 274 pages appear to be straight linear algebra that can be found in other books, including other Gilbert Strang books that I've taught out of before. I wonder why the publisher or the author felt the need to pad out this title with a introductory linear algebra treatment that is readily available elsewhere.


I have a question for the computer people out there. I have a programmer friend who, in the context of 3D virtual environments, came across the term "2 1/2 dimensional space". This has a specific meaning in mathematics: the Hausdorff dimension of a set can be a non-integer when it has fractal properties. For example, a set resembling a shoreline could have a Hausdorff dimension between 1 and 2, or a set resembling the face of a mountain could have a Hausdorff dimension between 2 and 3.

I remember vaguely that there are algorithms involving fractals or randomization for realistically rendering natural features like these, but don't know much about them. Does anyone else? And, when people in 3D graphics use the term "2 1/2 dimensional", are they using it in an informal sense, or does Hausdorff dimension actually arise in the description of these rendering algorithms?

Tuesday, May 20, 2008

He won't rest in peace if he hears this composition!

You may be able to tell from my most recent post that I derive great pleasure when a cache log is more than a simple "TFTC". This morning, incrediblemagpie was not the only creative cache finder. sparkyfry found my cache Rest in peace, Jaco Pastorius, a puzzle cache for which the hint is embedded in a piece of music that I "wrote". sparkyfry made a video of himself playing that piece of music on the piano, and I have been laughing about it all day. Take seven seconds out of your day to experience cache coordinates set to music, and be on the lookout for a version on bass guitar:

The End of (Mathematical) Days

As a mathevangelist, I am often asked, "Will I be among the Chosen when The End of Mathematical Days is upon us? Will I be carried into Pythagoras' Inner Circle for the rest of Eternity, or at least a Sufficiently Large Finite Approximation Thereof, and experience Pure Platonic Love?"

I reply, "It is true that not everyone can experience Pure Platonic Love. At the End of Mathematical Days, when the Reign of Mathematical Terror is lifted from Highland Park, Saint Paul, the Die will be checked, and to the Chosen Twenty will be revealed a mathematical truth beyond their wildest imaginings -- a sixth Platonic solid unlocking the mysteries of the universe."

Are you among the Chosen Twenty? Listen to the words of the recently admitted (thanks to incrediblemagpie):

Plato's Five Gems: Icosahedron

Verily as I enter the Valley Mathematical Terror,
I shall fear no equations:
For I have been endowed with the magical numbers.
Thy additions and subtractions, they comfort me.
Thou preparest a cache for me in the presence of mine enemies.
Thou annointest my head with clarity; my caches runneth over.

Surley keen vision and stamina shall lead me to all the caches of my life,
and I will dwell in the parks and fields forever.


The park is 1B's and all that cache in it,
the world, and those that hide in it;
for he has hidden it among the slabs,
and established it on slopes.

Who shall descend the slopes of 1B?
and who shall stand in his hiding place?
Those who have dirty hands and soiled knees,
who do not lift up their eyes to which is false, (decoys)
and do not swear deceitfully. (well at least not very loudly.)


To you, Oh 1B, I lift my pen.
Oh my 1B, in mathematics I trust:
do not let me be put to shame;
do not let caluclations exult over me;
Do not let those who wait be put to shame;
let them be ashamed those who are wantonly treacherous.(hehe)


Make me to know your ways, Oh 1B;
teach me your tracings,
lead me on your paths, and teach me,
for you are the 1B;
for you I cache all day.


Judge me, Oh 1B; for I have walked in the Valley of Mathematics;
I have trusted the numbers; therefore I did not slide.

Sometimes, I must remind the most eager seekers: "The park and the slopes and all that cache on them belong not to me but to mathematics. Lift your pen not to me but to mathematics. Endeavor to know not my ways but the ways of mathematics. It is for the tracings and paths of mathematics, and not I, that you cache all day. It is the austere logic of mathematics, and not mine, that judges."

Will you join the Chosen Twenty? Look within yourself, but also look here and here, for the signposts along your Platonic path.

Thursday, May 15, 2008

Deciphering Dad

I grabbed a cheesy men's magazine at the gym this morning, thumbed past the ads for clothes I wouldn't wear in a million years, and stumbled upon an excerpt of Augusten Burroughs' new book A Wolf at the Table: A Memoir of my Father. Later in the magazine was an essay by Michael Chabon, whose writing I prefer to Burroughs', but what caught my attention in the excerpt was Burroughs' mention of his father's interest in ham radio and the Q-codes that amateur radio enthusiasts use. His father chatted with strangers from far away, while right next to him his young son yearned for the same connection.

I thought of Wilco's 2002 masterpiece album Yankee Hotel Foxtrot. The climactic track on that album, "Poor Places", begins with Jeff Tweedy's words

It's my father's voice trailin' off
Sailors sailing off in the morning

and ends with a big knot of noise and a captured radio transmission of a woman's voice repeating Yankee... Hotel... Foxtrot... Yankee... Hotel... Foxtrot...

A meditation on the physical and interpersonal obstacles to communication.


After my grandfather's funeral, we returned to the line of cars with purple flags. My dad put his knurled hands on the steering wheel, exhaled, and opened the valve on emotions that he'd bottled for the previous weeks, months, years. I put my left hand on his shoulder, and he tensed -- an involuntary message that said "not now". The moment was too direct and too raw.

What's the comfortable language with my father? Golf, sports on TV, politics, and -- lately -- geocaching. Facts and tasks and made-up goals and little triumphs that serve as a sort of Q-code for underlying messages that are too direct and too raw to say out loud.


I found LucidOndine's puzzle cache Topsy Turvy after two failed attempts. I'll let the logs tell that story.

FSU*Noles' event Cup of Joe (Puzzle Edition) - Maple Grove! is Saturday morning. I'll be there at the Panera with close to 100 other geocachers and the muggles who love them.

Thursday, May 8, 2008

Endangering the lives of children... put me in the Star Tribune!

My wife and I have a nickname for the Star Tribune: "Dumb S*** Parents Do To Their Kids". Check it: every other day, someone is leaving their six-month-old kid in a parked car or a bathtub to go to a strip club or play video poker or shop online for shoes.

The dumb s*** I do, at least I do it to other people's kids. In 2002 I taught in a summer program at my former university. My course was called Geometry and the Imagination, and I thought it would help my ninth-grade students imagine some geometry if we built an icosahedron. That's a 3D shape with 20 triangular sides. Now, if I'm going to build the thing, I'm going to do it up right, with 2x2 lumber and bolts and nuts. OK, here come the pictures. It gives me shivers to look at these again.

Do you see any work gloves or goggles in this photo?

Somewhere there's a photograph of two 14-year-old girls grinning and holding 3/8" drills above their heads like it's the Wild Wild West, but luckily I couldn't find a copy of that photograph on the Wayback Machine.

Anyone who wasn't an oblivious mathematician like me looked at the structure and said, "You let ninth-graders use power tools?"

There's a mathematical mystery for you -- why did these parents let me near their children?

Wednesday, May 7, 2008

On embedded links and ticks

Last night I removed an embedded dog tick from my daughter's scalp. For an hour afterwards, I planned a blog post announcing that I was quitting geocaching forever, out of penance for exposing my children to harm. I went geocaching in Bloomington Sunday with Millah and LucidOndine and on the way home flicked four ticks off my own body. I assumed that she picked up a tick because I carried one into the house on my clothes.

But then I realized that she must have picked it up while she was doing somersaults in the grass outside the Roseville REI, and so for now geocaching need not be the fall guy.

I removed the tick with tweezers, gripping very close to the skin, pulling firmly and steadily. I verified that it was a dog tick and not a deer tick, verified that I removed the entire critter, and then cleaned the area with alcohol and killed the tick with alcohol -- and some gratuitous violence -- How dare you come into my house and attack my daughter like that?!

I have a small amount of tick experience: my wife and I celebrated our honeymoon in the spring of 2000 in the upper peninsula of Michigan, and I removed ticks from her on that trip. How romantic.

Is this what I have to look forward to during my first full Minnesota summer? My skin is crawling constantly. I think about ticks all the time. It hasn't been this bad since that unfortunate episode with chiggers when I was 15.

I have tentative spousal approval to go north for the MnGCA spring event the weekend of May 31. I haven't thought it out, though... nowhere to stay, no gear -- I sold it all or gave it all away when the kids came along -- and now I have this image of ticks up in the arrowhead driving their own pickup trucks and preying on soft city boys like me.


Silent Bob owned me. I present this story as a public service to others who, like me, have blogging aspirations and good intentions but a lack of knowledge about copyright issues.

Last Wednesday I attended WeekNIGHT Caching: 4 year anniversary and met Silent Bob among others. He took a picture of a beer glass pyramid that he made. I expressed regret at not getting a picture of it, and he said that I could use the one he took. At issue here is what exactly "use" means.

First I'll tell you what I did. The technical term for what I did is GANK. I ganked his photo. I downloaded a copy of his photo from his Flickr site and re-hosted it from my Blogger site. I thought that was okay, as long as I cited the photo as being from SB.

It is not. It is my very good fortune that SB chooses to spend some small amount of time looking at my blog, because he noticed my error and kindly pointed out the proper way to cite ownership of a photo. Much better that an acquaintance do this than a complete stranger. Let me see if I can describe this correctly.

SB uses the Creative Commons license specifying Attribution-Noncommercial-No Derivative Works, which means roughly that I can use his photo, as long as I attribute it to him (in the way I'll describe below) and do not mash it up and do not use it for commercial purposes.

Instead of re-hosting the photo on my site, I should instead link to the original hosting site and state that the photo was originally uploaded by him. Look at the page source of the post in question for an example of how to do this.

(A quick question as an aside: I've heard the practice of linking to content offsite called "stealing bandwidth". Is this a lesser transgression than ganking the photo? I guess it is. That asked, I didn't gank the photo with that in mind. I just plain didn't know.)

I removed some other photos from my site and in the future I will either search for photos that carry the Attribution or Public Domain CC license or I will think about how a photo of my own may enhance my post. Time to clean up my cache pages, too.

SB also alerted me to this much higher profile version, on Aaron Landry's blog, of what I did. Interesting reading, especially in the comments, and especially if you're a reader of Boing Boing, which you probably are. Or should be.

So, a big public hats-off to SB for schooling me gently and introducing me to CC. It's about time I learned, because I encounter a lot of content in my academic job that is licensed under Creative Commons.


Heading out to Chanhassen for Weeknight tonight. After I tried to intimidate everyone on the MnGCA forum mathematically, and Lucid tried to intimidate me as a moderator, we'll see who is more intimidating in person! It's on!

Friday, May 2, 2008

Geek Summit

I was a lonely fifth-grader. Intricate, baffling, and scary social patterns were developing in front of my eyes. I liked girls, and apparently some liked me, but I couldn't understand how I could receive a note at the beginning of recess saying

"Will you go with Hilary? Circle YES or NO."

and after circling yes and wondering what I should do next -- How do you "go with" someone? Should I go say hello to her? -- receive another note 15 minutes later saying

"Hilary doesn't want to go with you anymore."

So long, Hilary. "We'll always have Recess".

But a benevolent teacher recognized that I had different interests from most of my classmates and that another student at the neighboring elementary had different interests, and so she organized a Geek Summit. I went to Scott's house to play trumpet and clarinet and role-playing games and historical-simulation games and talk about Star Trek -- I never understood the appeal, and still don't, but I secretly admired that he continued to wear his Star Trek logo T-shirt to school every day despite endless ridicule.

Thus began my pursuit of social connections based on interest rather than happenstance geography, and I view my time spent on the internet -- blogging, forums, logging caches -- as a more efficient environment for that.

I'm not here to become a local authority on geocaching. In fact, I would love to see many more active blogs added to the mix. I'm not here to make money. In fact, it could be argued that this hobby results in a net loss in income. I'm here instead to hang a sign that says: here's a little bit of who I am and what my interests are. Take it or leave it. Maybe it will result in a new social connection. Maybe it won't.

All internet content either conveys factual information -- such as Wikipedia (and before the joke forms in your head, it's factual even if it's wrong) -- or conveys opinion and personal information -- such as Facebook pages and Twitter posts.

That's why it's a bit confusing to see this debate over the role of sports bloggers become so heated. It's disappointing to see Buzz Bissinger act so bitter and defensive, because his book Friday Night Lights about high-school football in Texas is so well-written. What's a sports blog? It's a virtual bar, basically. You go there to share opinions about something you're all interested in, and it turns out that most of the people are dips***s, but that's the price of the efficiency of the social environment. It doesn't threaten sports journalism; it sustains the need for it.


Latest Geek Summit: weekNIGHT Caching: 4 year anniversary on Wednesday. Was in close geographic proximity to -- no chance I'm hyperlinking all these -- TheCollector (the event's organizer), Millah, shoestorm, Plem45, DogSoft, MN_Cavepeople, topgear, broken tooth, bflentje, casinoman, sir_zman, two of hearts, Oneied Cooky, minnesotabrad, TECGeoJim, MSPMatt, speedysk1, Arcticabn, Good-Boy, and ultimately LucidOndine, Celticwulf, and Silent Bob.

Just like fifth grade, except with beer. Lots of beer.

Beer glass pyramid
(originally uploaded by Bill Roehl) (L-R: LucidOndine, SB's pyramid, Celticwulf's left shoulder)