Saturday, July 11, 2009
Monday, September 29, 2008
Sore.
The Boy and I went backpacking this weekend. Awesome. It was a 10 mile loop with a back country campsite at the half way point. I forgot to take a camera, so the only photos I took were with my cell phone camera. I'll put up a picture of the boy fully loaded once I get it off my camera.
I rented a kids backpack at REI that was so close to small enough for The Boy. I thought about buying it, but figured we should rent it first and see how it went. I'm glad I rented first. He is so skinny that it was really tough to get it to sit properly on his hips. As a result, we were constantly tweaking the adjustments trying to move the load onto his legs, and not his shoulders/back. Plus the padding at the back of the hip belt didn't work right on his short torso. The stay sort of dug into his bum, and really started to bother him after about three miles on the hike back. He needs to grow a bit (maybe an 1" in his torso and 2" around the waist) before this pack will fit him properly. If anybody knows of a rucksack with a proper hip belt that can fit a small child (11.5" torso), let me know.
His pack was 10 lbs. My pack was about 35 lbs. So by pack/body weight ratio, he worked harder than I did by just a bit. We both made it all the way. Go us. The weather couldn't have been better. It was spectacularly dark (no moon), and cool enough to sleep comfortably at night. The tent was really roomy with just the two of us.
So, now we are both home, and my legs are sore. I was surprised at how much effort it took.
In other news, my two week trip to Switzerland/England went well. Going back to Sheffield was a bit strange. Kind of like that feeling you get when you would go home after being at college all year. Sort of a "yeah, this is my other home" feeling. I closed my UK bank account. I think that was my last solid tie of residency. I did some walking in The Peaks and bouldering at The Climbing Works. The Climbing Works rocks, and I wish it were in St. Louis.
I rented a kids backpack at REI that was so close to small enough for The Boy. I thought about buying it, but figured we should rent it first and see how it went. I'm glad I rented first. He is so skinny that it was really tough to get it to sit properly on his hips. As a result, we were constantly tweaking the adjustments trying to move the load onto his legs, and not his shoulders/back. Plus the padding at the back of the hip belt didn't work right on his short torso. The stay sort of dug into his bum, and really started to bother him after about three miles on the hike back. He needs to grow a bit (maybe an 1" in his torso and 2" around the waist) before this pack will fit him properly. If anybody knows of a rucksack with a proper hip belt that can fit a small child (11.5" torso), let me know.
His pack was 10 lbs. My pack was about 35 lbs. So by pack/body weight ratio, he worked harder than I did by just a bit. We both made it all the way. Go us. The weather couldn't have been better. It was spectacularly dark (no moon), and cool enough to sleep comfortably at night. The tent was really roomy with just the two of us.
So, now we are both home, and my legs are sore. I was surprised at how much effort it took.
In other news, my two week trip to Switzerland/England went well. Going back to Sheffield was a bit strange. Kind of like that feeling you get when you would go home after being at college all year. Sort of a "yeah, this is my other home" feeling. I closed my UK bank account. I think that was my last solid tie of residency. I did some walking in The Peaks and bouldering at The Climbing Works. The Climbing Works rocks, and I wish it were in St. Louis.
Friday, September 5, 2008
Circle Puzzle Answers
This puzzle ended up being much more popular that I anticipated. Aside from the comments on the blog, some coworkers and other friends that don't post got into it. The name of the puzzle is Bertrand's Paradox.
rpc did some of the math wrong, but did point out another solution. If you randomly pick the cord and then orient the circle so that the cord is vertical, then all cords between x=-1/2 and x=1/2 are longer then sqrt(3). Therefor, the probability is 1/2.
The third classic answer is that the midpoint of the cord uniquely defines the cord. So, we randomly pick a point inside the circle and construct a cord so that that point is the midpoint of that cord. Now, any point we pick inside the circle of radius 1/2 is longer than sqrt(3), and outside is shorter. Comparing the inside area of the circle to the area of the whole circle gives a probability of 1/4.
Now rpc did the most work on this, and some of his ideas were on track to a cool outcome. He and I did some discussions at climbing on Tuesday, and he cleaned up the reasoning so that we can now cover all probabilities on the interval (0,1). It's not [0,1], just (0,1) because I wouldn't let him do constructions at infinity. I've modified it a bit from what rpc came up with. He used two constructions to cover (0,1/2) and (1/2,1), and then we filled in 1/2 with the previously mentioned case. I figured out a way to do a single construction to cover (0,1).
Start with the vertical line at x=-1. Pick a point at (n,0) where n>1 (but finite). Draw a line tangent to the circle from (n,0) to (-1,y); y>0. Randomly pick a cord, and then orient the circle so that one end of the cord lies at the point (-1,0) and the other point is oriented so that its y coordinate is positive. Now create a 1-to-1 and onto mapping (bijective) of every cord to a point on the tangent line (n,0);(-1,y) via the cord's projection. Because it is bijective, it is equivalent to randomly pick a point on the tangent line and look at the probability that the associated cord is longer than sqrt(3).
If n is very close to 1, then y is very large, and most points on the tangent line are associated with cords of length less than sqrt(3). If n is very large, the y is very nearly 1, and most of the cords will have length more than sqrt(3). Given any probability desired over the inteval (0,1), a tangent line can be constructed that gives a bijective map with that probability.
It is not an ill defined problem. The problem is that there are an uncountably infinite number of cords on the circle. I can create an uncoutnably infinite set of mappings of cords to the interval [0,1] such that I can get the probability to be whatever I want.
I don't let n be equal to 1 or infinity, because then I can't map the cords to the inteval [0,1], which seems necessary to get any sense of the problem (which fraction of the interval maps cords of length more than sqrt(3)). But since n>1, and n is finite, I get the full range of probabilities from (0,1).
Super duper extra credit to rpc for inspiring this solution.
rpc did some of the math wrong, but did point out another solution. If you randomly pick the cord and then orient the circle so that the cord is vertical, then all cords between x=-1/2 and x=1/2 are longer then sqrt(3). Therefor, the probability is 1/2.
The third classic answer is that the midpoint of the cord uniquely defines the cord. So, we randomly pick a point inside the circle and construct a cord so that that point is the midpoint of that cord. Now, any point we pick inside the circle of radius 1/2 is longer than sqrt(3), and outside is shorter. Comparing the inside area of the circle to the area of the whole circle gives a probability of 1/4.
Now rpc did the most work on this, and some of his ideas were on track to a cool outcome. He and I did some discussions at climbing on Tuesday, and he cleaned up the reasoning so that we can now cover all probabilities on the interval (0,1). It's not [0,1], just (0,1) because I wouldn't let him do constructions at infinity. I've modified it a bit from what rpc came up with. He used two constructions to cover (0,1/2) and (1/2,1), and then we filled in 1/2 with the previously mentioned case. I figured out a way to do a single construction to cover (0,1).
Start with the vertical line at x=-1. Pick a point at (n,0) where n>1 (but finite). Draw a line tangent to the circle from (n,0) to (-1,y); y>0. Randomly pick a cord, and then orient the circle so that one end of the cord lies at the point (-1,0) and the other point is oriented so that its y coordinate is positive. Now create a 1-to-1 and onto mapping (bijective) of every cord to a point on the tangent line (n,0);(-1,y) via the cord's projection. Because it is bijective, it is equivalent to randomly pick a point on the tangent line and look at the probability that the associated cord is longer than sqrt(3).
If n is very close to 1, then y is very large, and most points on the tangent line are associated with cords of length less than sqrt(3). If n is very large, the y is very nearly 1, and most of the cords will have length more than sqrt(3). Given any probability desired over the inteval (0,1), a tangent line can be constructed that gives a bijective map with that probability.
It is not an ill defined problem. The problem is that there are an uncountably infinite number of cords on the circle. I can create an uncoutnably infinite set of mappings of cords to the interval [0,1] such that I can get the probability to be whatever I want.
I don't let n be equal to 1 or infinity, because then I can't map the cords to the inteval [0,1], which seems necessary to get any sense of the problem (which fraction of the interval maps cords of length more than sqrt(3)). But since n>1, and n is finite, I get the full range of probabilities from (0,1).
Super duper extra credit to rpc for inspiring this solution.
Friday, August 29, 2008
A Probability Puzzle
I had my first day of classes towards my D.Sc in Systems Science and Mathematics. I'm taking "Probability and stochasitc processes". Just to convince us that the idea of "probability" is not trivial (and also that this class could very well kick our collective asses), the professor posed this problem. Super bonus points to any one that can give the complete answer (without cheating on Google).
Start with the unit circle. Randomly select a cord, AB. What is the probability that the length of the cord is greater than sqrt(3)?
If you are brave post your answer in the comments. Extra credit for showing your work. I don't think anybody in the class really "got" the answer. Or at least all of it. I got one part of it, probably the easiest part.
Start with the unit circle. Randomly select a cord, AB. What is the probability that the length of the cord is greater than sqrt(3)?
If you are brave post your answer in the comments. Extra credit for showing your work. I don't think anybody in the class really "got" the answer. Or at least all of it. I got one part of it, probably the easiest part.
Monday, August 11, 2008
New Post
Is anybody checking this?
It's been a while since my last post, and lots has happened. I don't even know where to start.
1) I bought a new grill this weekend. I haven't consummated the relationship yet, but plan to Wednesday. I got the Jenn-Air that Consumer Reports liked (#4), is pretty stainless (3oo series!), and was massively discounted at Lowe's for end of season clearance. Yeah!
2) I've been struggling with the lawn this year. Today I went out to the front yard and saw that a nest had been formed in a patch that some ants had destroyed. I figured the ants were back, so I went again to destroy the nest. That's when I saw that it wasn't ants. Tiny bunnies that didn't have their eyes open yet. Probably five of them. Amanda convinced me not to destroy them. I'm not sure I really could have. So, the grass will grow long for a week or two while the bunnies get big enough to hop away.
3) I gave a presentation on effective technical communication a couple of weeks ago at a work conference. I won one of the best presentation awards, which bugs me. Some of it is the irony. Mostly its the fact that the judging criteria was 50% technical content, of which I had basically none (not a technical topic). The award was not so much a reflection of how well I did, but how poor the other presentations were.
4) Amanda finally relinquished her old laptop to me. Ubuntu is up and running. A very accommodating OS for the masses. I've had to tweak two things total I think. Not bad for Linux. Right now I'm using the desktop, 'cause I still love a full sized keyboard for any real typing.
5) I just got back from DC. It went great! I think I will be joining the ANSI B5.54 standards committee. Yeah! I might contribute to an industry standard. How's that for geek-cred. Also, I (and another guy) came up with a wicked cool implementation for "optimally" sizing the G and Q matrices in a damped least squares controller. Like LQR, but not iterative. I'm going to see if it is publication worthy.
6) I'm about to start my D.Sc. I have a class picked out for fall, but I still need to register. I also need to go over my proposed curriculum with the department chairman, and see if it will work. It mostly hinges on getting my Master's work to count. I should have my doctorate degree by end of 2012. I think. It's scares the hell out of me.
7) I pulled my shoulder several weeks ago, and it is still not back 100%. This sucks, as it has affected my climbing. I'm totally plateaued at 5.9, and can't seem to get to 5.10. It's too hot to run, so I've tried doing some swimming at the Y. By tried, I mean I've gone once. My conditioning is off and my strength is mediocre because I can't load my shoulder. Frustrating.
That can't possibly be all, but hopefully it gives a clue as to what is going on in my life.
Oh, I bought the Ety's and they rock. I never did go backpacking, but I did take the kids camping and we had a great time. Longs Peak is postponed for a year. Still a goal.
It's been a while since my last post, and lots has happened. I don't even know where to start.
1) I bought a new grill this weekend. I haven't consummated the relationship yet, but plan to Wednesday. I got the Jenn-Air that Consumer Reports liked (#4), is pretty stainless (3oo series!), and was massively discounted at Lowe's for end of season clearance. Yeah!
2) I've been struggling with the lawn this year. Today I went out to the front yard and saw that a nest had been formed in a patch that some ants had destroyed. I figured the ants were back, so I went again to destroy the nest. That's when I saw that it wasn't ants. Tiny bunnies that didn't have their eyes open yet. Probably five of them. Amanda convinced me not to destroy them. I'm not sure I really could have. So, the grass will grow long for a week or two while the bunnies get big enough to hop away.
3) I gave a presentation on effective technical communication a couple of weeks ago at a work conference. I won one of the best presentation awards, which bugs me. Some of it is the irony. Mostly its the fact that the judging criteria was 50% technical content, of which I had basically none (not a technical topic). The award was not so much a reflection of how well I did, but how poor the other presentations were.
4) Amanda finally relinquished her old laptop to me. Ubuntu is up and running. A very accommodating OS for the masses. I've had to tweak two things total I think. Not bad for Linux. Right now I'm using the desktop, 'cause I still love a full sized keyboard for any real typing.
5) I just got back from DC. It went great! I think I will be joining the ANSI B5.54 standards committee. Yeah! I might contribute to an industry standard. How's that for geek-cred. Also, I (and another guy) came up with a wicked cool implementation for "optimally" sizing the G and Q matrices in a damped least squares controller. Like LQR, but not iterative. I'm going to see if it is publication worthy.
6) I'm about to start my D.Sc. I have a class picked out for fall, but I still need to register. I also need to go over my proposed curriculum with the department chairman, and see if it will work. It mostly hinges on getting my Master's work to count. I should have my doctorate degree by end of 2012. I think. It's scares the hell out of me.
7) I pulled my shoulder several weeks ago, and it is still not back 100%. This sucks, as it has affected my climbing. I'm totally plateaued at 5.9, and can't seem to get to 5.10. It's too hot to run, so I've tried doing some swimming at the Y. By tried, I mean I've gone once. My conditioning is off and my strength is mediocre because I can't load my shoulder. Frustrating.
That can't possibly be all, but hopefully it gives a clue as to what is going on in my life.
Oh, I bought the Ety's and they rock. I never did go backpacking, but I did take the kids camping and we had a great time. Longs Peak is postponed for a year. Still a goal.
Sunday, May 25, 2008
Backpacking
I was planning on going backpacking next weekend. So far two potential camping mates have bailed out on me. Does anybody want to go backpacking? You'll need a backpack and a sleeping bag, but that's about it. Everything else I have. I may take the girl if no one else wants to go. I made a trip to REI today to get the last bit of kit that I would need. I'm itching to go before it gets insanely hot here. The tentative plan is a moderate 5 mile hike in and out. Ten miles total over two days. You barely have to be in shape for that. C'mon, join me in ditching the world. If your up for a longer treck, I'm more than happy to do a 25 mile loop or out-and-back on the Ozark Trail.
My brother in law got me The Orange Box. Portal is of course genius and I'm working on the Bonus maps now and then. However, TF2 is sucking away my free time. Damn him. I suck, but I have loads of fun. I manage to stay alive for about two minutes on average. I tend to average probably just over 1 kill per life, so I guess I'm causing more harm then I'm taking. Right now I'm trying to get better at rocket jumping. I tried being a spy for all of about 30 seconds.
We are switching to AT&T U-verse. From the reviews that I am reading online, I think I'll be happy with the switch. Especially getting better bandwidth. I also signed up for the HD package. Although from what I read, it's a highly compressed lower bandwidth version of HD that isn't as good as other providers. It's $10/month, but if it sucks I can drop it.
My brother in law got me The Orange Box. Portal is of course genius and I'm working on the Bonus maps now and then. However, TF2 is sucking away my free time. Damn him. I suck, but I have loads of fun. I manage to stay alive for about two minutes on average. I tend to average probably just over 1 kill per life, so I guess I'm causing more harm then I'm taking. Right now I'm trying to get better at rocket jumping. I tried being a spy for all of about 30 seconds.
We are switching to AT&T U-verse. From the reviews that I am reading online, I think I'll be happy with the switch. Especially getting better bandwidth. I also signed up for the HD package. Although from what I read, it's a highly compressed lower bandwidth version of HD that isn't as good as other providers. It's $10/month, but if it sucks I can drop it.
Wednesday, May 7, 2008
Oh Canada!
(OMG, a new post!)
I'm in Canada. Specifically Waterloo, Ontario. I went bouldering tonight at a local gym. I like it that my climbing shoes take up basically no room in my suitcase and most cities have a climbing gym somewhere nearby. Climbers are a friendly bunch, and it's easy to start tackling a problem with one or two others. Even for an introvert like me.
(heh, they just said "aboot" on the radio)
At home I've been busy. Gardening, closets, a mysterious water leak, slab for the grill, trips to Illinois. I like to keep busy, so no complaints by me. What I've been struggling to find in this is solitude. Here and there some alone time, but not solitude. I noticed this on the flight up. The plane was mostly empty. I guess nobody flies to Toronto from St. Louis. So, I was in a row to myself. Headphones in (same Sony ones as before). Reading my new book. And I was relaxed. Really, really relaxed. There was nothing I needed to get done, no external pressure. I could just be solitary on the plane. It was very enjoyable.
The book I picked up is the Presentation Zen book. I'm only a bit into it. I'm reading it slowly and my mind wanders to my own presentations while I read it. I'm probably getting less out of it then someone who doesn't already know Garr Reynolds approach. But still, it's nice to have it all written down in book format. I can recommend (and lend) it to you if you want to really change your presentations to not suck. It's work. It's not a formula or a procedure but a new way to think about the form and function of presentations. It has basically nothing to do with PowerPoint, and everything to do with story and design. Conferences would be much better if everyone really worked on their presentations. I had to sit through a few today. Slideuments so typical and boring that I don't even bother listening since I know I'll get a CD with all the words later and I can pretend to care then.
A few more days with our neighbors-to-the-north. Endless hockey on Sports Center. Lousy food, but very cold beer. Great sunshine. Then back to St. Louis. I'll try to keep writing.
I'm in Canada. Specifically Waterloo, Ontario. I went bouldering tonight at a local gym. I like it that my climbing shoes take up basically no room in my suitcase and most cities have a climbing gym somewhere nearby. Climbers are a friendly bunch, and it's easy to start tackling a problem with one or two others. Even for an introvert like me.
(heh, they just said "aboot" on the radio)
At home I've been busy. Gardening, closets, a mysterious water leak, slab for the grill, trips to Illinois. I like to keep busy, so no complaints by me. What I've been struggling to find in this is solitude. Here and there some alone time, but not solitude. I noticed this on the flight up. The plane was mostly empty. I guess nobody flies to Toronto from St. Louis. So, I was in a row to myself. Headphones in (same Sony ones as before). Reading my new book. And I was relaxed. Really, really relaxed. There was nothing I needed to get done, no external pressure. I could just be solitary on the plane. It was very enjoyable.
The book I picked up is the Presentation Zen book. I'm only a bit into it. I'm reading it slowly and my mind wanders to my own presentations while I read it. I'm probably getting less out of it then someone who doesn't already know Garr Reynolds approach. But still, it's nice to have it all written down in book format. I can recommend (and lend) it to you if you want to really change your presentations to not suck. It's work. It's not a formula or a procedure but a new way to think about the form and function of presentations. It has basically nothing to do with PowerPoint, and everything to do with story and design. Conferences would be much better if everyone really worked on their presentations. I had to sit through a few today. Slideuments so typical and boring that I don't even bother listening since I know I'll get a CD with all the words later and I can pretend to care then.
A few more days with our neighbors-to-the-north. Endless hockey on Sports Center. Lousy food, but very cold beer. Great sunshine. Then back to St. Louis. I'll try to keep writing.
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