Despite comments requiring moderation before posting, I’ve had a flood of thousands of spam comments over the last few days in the queue and I’m tired of pressing the delete button. Thus, they are disabled for the time being until I can set up something more automated.
Sorry spammers, none of those posts ever made it to any web crawler.
Update: or not. Of course WP makes this hard. Well you can’t comment on this one post at least!
I finished reinforcements on my facet kite about a month ago, and there my project sat as I waited for supplies to come in. Last Thursday the shipment arrived, so when I got a free hour this weekend, I did the edge binding on four of the eight panels. On all of my previous kites, I used double-folded hems, where, as the name suggests, you fold the edge of the sail over twice and then sew it flat. With edge binding, you instead fold and sew a separate piece of material along the cut edge. Edge binding seems like it would be easier, but I find that it’s a bit of a battle to keep the sail and binding material aligned. Perhaps some sticky tape would help, but that just adds to the build time. On the other hand, binding can look nicer since the border stands out.
After I finish the bindings, there’s a bit more sewing, and then it’s ready for framing and its first flight.
So the blog mysteriously committed suicide recently, so I took the opportunity to update to the latest WordPress. Everything now seems to be in order. Perhaps I should also upgrade the theme one of these days.
Also committing suicide this weekend was the two year old Ubuntu installation on my laptop. The automatic upgrade to 10.04 resulted in a non-bootable mess (it turns out this was merely foreshadowing), so I took a backup and then dropped the F15 alpha on it to see what the Gnome3 Shell hubbub is all about. It does make my computer feel like a giant cell phone, but I do actually hate it less than I thought I would. We’ll see if that faint praise holds up after I use it a bit. The actual F15 installation took four tries, all due to my Macbook’s quirky half-EFI, half-BIOS firmware. No manner of coercion would convince Fedora to make a hybrid GPT/MBR partition table that actually booted, so I eventually gave up and just created a plain MBR with fdisk and that was that. A full day of reloading the backup and updating packages later, and I am back to a functional desktop, sans all those pesky minimize buttons.
Occasionally, rewriting other people’s code can be its own reward:
88 times speedup is not too bad for a few days’ work.
I’m just going on record to state that the two reasons I’ve seen on the net for lack of tree-based collections in the Python standard library — (1) that they have bad locality (gee, very unlike huge memory-hogging randomized hash tables, oh and just try scanning one of those…), and (2) that Python makes it so simple to write your own, just do that! (well, yes I can and have, but hey it’s 2011 already, rbtrees are like 40 years old!) — are inane.
It’s almost spring and that means time to make another kite! I haven’t done one in a couple of years so hopefully I haven’t lost all of the necessary sewing skills. This time around I’m going with a cellular design (think box kite), the #54 star facet. This morning I spent about half an hour on the first step — cutting out the necessary shapes from rolls of ripstop nylon. We have an enclosed area with great big sunny windows in our apartment which are perfect for tracing the shapes out onto the material.
The next step is adding reinforcements and binding for which I’m waiting on supplies. The Cherry Blossom nee Smithsonian Kite Festival is coming up in a couple of weeks so I want to get it all done by then. I can’t wait to see what Alex thinks of kite flying!
I bought a new wireless router the other day, a D-Link DIR-825 dual-band a/g/b/n. This is a step up in several regards from my previous 2.4 GHz 11g Linksys, not least of which is the D-Link’s ability to run OpenWRT with ath9k. Installing OpenWRT with prebuilt binaries is dirt simple; it took all of about 5 minutes to set up.
One of my motivations was to do some IPv6 testing in advance of World IPv6 Day. Comcast doesn’t yet offer IPv6 addresses to the public at large, so I set up a Hurricane Electric 6in4 tunnel. This is quite easy to configure in OpenWRT.
So now I can load ipv6.google.com in my browser. It’s approximately 2 better than the normal site.
An unassuming cardboard tube arrived in the mail the other day, containing my MSCS diploma from Hopkins. Thus passes my academic career. I doubt the experience will ever pay for itself financially, but I did learn a great deal, even as a crusty practitioner of some years. Returning to the student life of never-ending deadlines took quite some getting used to, and the corresponding lack of sleep was good training for Alex’s concurrent arrival. (Said arrival also made up my mind to not pursue the thesis option.)
In the main, the classes were excellent, but the small size of the school means the catalog is limited compared to Georgia Tech. For example, I would have liked a class or two on the hardware side. Hopkins only offered the equivalent of GT’s CMPE 2510 (MIPS architecture with the Hennessy and Patterson book).
Through projects and reading papers, I gained a new appreciation for the difficulty of good science, and the prevalence of bad. I’ll always be an engineer first, as I lack the patience to do science well. Banging out a project out in 2-6 weeks was de rigeur; here are some of them:
There are of course writeups associated with all of these, but my latent inner perfectionist is not very happy with most of them. I might revisit them with more rigor if I get bored some day.
In C, scoping rules aside, the following are pretty much the same:
static int x[] = { /* ... */ };
int foo()
{
/* do something with x */
}
and
int bar()
{
static int x[] = { /* ... */ };
/* do something with x */
}
The static array x will go into the .data section of the executable. When the OS loads the executable into memory, it will ensure that the values for x are set in the appropriate place (e.g. by mapping its disk page to the virtual address in the ELF headers). In the second case, x is given some alias to avoid symbol conflicts.
There seems to be no way to do the second version in Java. Here’s how I tried:
static int xyzzy()
{
final int x[] = { /* ... */ };
/* do something with x */
}
This doesn’t do what you might think it does. While x cannot be changed, it is the reference to an array; the array elements themselves can be changed at will. Thus javac is unlikely to do anything smart here.
Indeed, in the above case, javac will initialize x with stack pushes every time xyzzy() is called. I had a real method like this, and making x a static member variable gave me an easy 2x speedup.
Last night I had the pleasure of driving my car less than a mile from the nearby metro to our apartment, during a heavy snow, in rush hour. Normally I walk, but this area is bad about keeping sidewalks clear in snowy weather, so driving is sometimes the safer option. It took me an hour and a half to cover the distance, at a blazing average speed of 2/3 mph.
Along the way I learned some unwritten rules of driving in DC snowstorms: