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Sapphire Cat
sapphirecat
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July 2006
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www.sapphirepaw.org/blog

I have my head working on some sort of way to model gas consumption from a car. The basic question is: given a set of gears, what's the most economical way as measured in miles per gallon to accelerate? By and large, gas consumption is determined by engine RPM(*), which is tied through the transmission to velocity. Higher gears give lower RPM, and holding velocity constant, that translates directly to better gas mileage.

The question becomes: is it better to accelerate hard in a lower gear, then shifting up late, boosting consumption but packing it over a shorter time? Or is it better to shift as early as possible, spending more time accelerating more slowly in intermediate gears?

It's a surprisingly difficult problem. There's a nonlinear relationship between torque and RPM, along with certain limits on how much acceleration one can actually realize given the road condition. But once I find all the knobs to twist, it should provide hours of entertainment. ;-)

* The only statistically significant factor in my gas studies was driving for minimum average RPM, by traveling as much as sensible in neutral, especially on higher-speed roads. How "hard" the engine works, or how fast you drive (40 vs 60) don't really matter as long as it's the same gear in both cases. I am forced to conclude, as the gas pedal feedback suggests, that the line between working the engine lightly (engine braking) and heavily (acceleration) is a trivial amount of gas, and running to keep at the exact same speed is a fairly critical equilibrium.

It has come to my attention that Bash 3.0 has an option called 'pipefail'. This option, when engaged, changes a pipeline's exit status to be the status of the last failing command, instead of the last command. First things first: what if this failing is a cascade error? Wouldn't you like to know the exit status of the first command that failed, along with what it was? (Perhaps indicated as a position in a pipeline.)

pipefail is obviously a Bash-specific option, so why can't the full power of bash be leveraged in the first place to provide useful return codes? For instance, why can't the full array of exit codes be returned in some way, with vanilla $? remaining the last exit code of the pipe, for compatibility?

Say no to brain damage. Use ksh... or Perl where Perl is warranted. pipefail is the kind of bogus decision I would expect from PHP.

I have Internet again. Minimum SNR required for DSL: 6.0. Actual SNR: 26.0-30.0. Not bad for an address that, on my first call, was "not eligible" for DSL.

I've been having problems getting modern 2.6.16 kernels to boot. The SATA drive is apparently AWOL, as /dev/sdaX doesn't actually contain the root partition. (It hasn't moved to sdeX, hdaX, or hdeX either.) So of course the thing panics. You can't do anything to find out where the root partition actually is. You can't scroll back up the output because panics were meant to represent "Trust nothing", and so the scrollback buffer and keyboard driver have run away screaming. Like me.

Gentoo-sources seems to have some sort of patch that quietly conflicts with the NVidia binary drivers. (Lo, I am unclean, for I hath used a piece of NonFree(TM) Software.) It was improved by going to no-preemption, 100 HZ clock, and running without network, but vanilla 2.6.16 has yet to crash.

I still find the current Netfilter/iptables configuration Byzantine, complicated, and maybe chock full of forward references.

I reshuffled my drive beneath my feet, from [swap /:reiserfs /home:reiserfs netbsd-3] to [swap /boot:ext3 /:ext3 free]. Of course /home now lives on the / partition. Maybe it sounds like the "Marine" mentality that Edward Yourdon despises, but one puts in extra care rewriting partitions and copying data between them when one's last backup was almost a month ago.

Operating a house is like an extra part-time job. I haven't vacuumed or cleaned the bathroom since moving in. Or mowed the lawn. I'm getting clover in the front yard.

(funcall #'sleep (hours 16) cat) ; or so

Feel .:: rambly

Freakonomics by Steven D. Levitt and Stephen J. Dubner is an excellent read, and highly recommended. In the "stayed up until 3:30 AM reading it" kind of way.

Due to the personal involvement of a family friend, I'm going to give Alltel one more chance to screw up my Internet service, then I'm going to have to go with Roadrunner. There may be no worse company on the face of the planet than Alltel (currently spinning off and rebranding themselves as Windstream Communications).

I ran a chunk of wire from a box by the furnace to an outlet in the dining room, more or less smack in the middle above the furnace. 14-2-W/G runs out from the breaker box, across the basement, to the light by the laundry, back to the middle, over past the furnace, into the box in question, and over to another corner (diagonally opposite the breaker box) for a shoplight and pair of outlets on what must have been a workbench. The five feet between the furnace box and the actual outlet was some old 14-2 ungrounded BX wiring. It's like running a dedicated OC3 to every house, except it's terminated at the curb and switches to Cat3 to go inside the house.

My employers graciously let me come in on off hours to use the Internet. I was looking into the terms and conditions of HSBC's online savings account (currently with l33t 5.05% APY). If the bank is in any dispute, or any third party happens to make a claim to your account, in any jurisdiction, even if you aren't involved in the proceedings at all, the bank can reimburse itself for its trouble by taking funds out of your account. Of course they have to mail out a notice, but there's a time delay between mailing and receiving, during which one could be writing rubber checks. Not to mention that some companies are relatively slow about cashing checks, so they could start their life good but turn rubber before being cashed. Then the bank turns around and limits their liability on errors to the interest that would have been paid on the funds in question. Presumably, the funds themselves are Just Gone™.

Frankly, if someone's going to be in charge of a chunk of my money, they shouldn't be able to go around saying "Hey, it's your problem if we mess up." It separates the motivation to prevent errors from the capability to do so.

Feel .:: busybusy

Note: These pictures have not been selected for technical excellence or brilliant artistic composition. They are instead amateur-quality crops of even uglier frames, and one might count oneself blessed that I even bothered to sharpen them.

Ready to go!Collapse )

Feel .:: blankblank

A lot of people (co-workers and customers alike) complained about their general lack of money at the gas station. Yet, behind their voice lies a quiet determination not to do anything about it. If someone values barhopping or lottery more than having the money, then that's where their money will go. They're not saying, "I'm willing to make that trade. No more bars, no more woman-chasing, I'm going to worry about getting richer."

I have to wonder if they even believed they could get richer if they tried. I never once thought about traveling abroad until I was in college, and someone asked me if I was going to. Although I didn't see it at the time, my way of thinking about the world was much like my parents': a destination to an exotic locale for a vacation would be somewhere like Lake Placid, at the other end of the state. Somewhere we could drive in a day or so.

Now that I've read Rich Dad, Poor Dad by Robert Kiyosaki, I'm looking at my financial state and thinking, "This isn't so bad, actually." I can get plenty richer than I am now, if my fiancée and I are willing to make those tradeoffs and play the game that way.

At the gas station, we would occasionally get an extra paycheck in a month, when we got paid the first, third, and fifth Fridays. As soon as that third check hit their hands, all the talk of "If I had money" from the others evaporated and more shortsighted purchases would happen.

Maybe it sounds trite or glib, but it truly is impossible to do (or finish) anything without the belief that it can be done, and that the only obstacle is finding the way.

I made a decision a while ago. When the paid time on this journal runs out, I'm going to revert to a free account and leave it at that. I've also quit developing on my LJ client. (Not that that was worth much. Before LJ quit posting stats, only about 40 people had ever tried it, and I might have 5 actual users.)

In real economic terms, I paid for LJ because it was completely ad-free. What little value I derive from the paid features is not enough to justify continuing to buy paid time, especially in the face of the Sponsored+ betrayal.

This is unrelated to recent events, but those events are the catalyst for making this post.

UPDATE: I realized last night that if I quit paying for LJ, I could spend the $25 on the Sharebuilder IRA management fee. A much, much better deal.

I've just spent 16 hours of work time researching, setting up, and generally banging my head against the wall with setting up Postfix 2.2.7 to filter only inbound mail through dspam.

  • In a sufficiently complicated setup, it's not a good idea to have dspam share a uid table with anything. Due to forwarding aliases, you'll end up with either a uid for each alias, or remote usernames cluttering up the virtual mailbox table.
  • It's probably not a good idea to filter outbound mail through dspam, so you'll want two IP addresses and two instances of Postfix to separate the inbound pipe (pointed to by MX records in DNS) and outbound pipe (pointed to by mail client configuration). The minimal collection of files to configure a Postfix instance is main.cf, master.cf, postfix-files, postfix-script, and post-install in the config directory, and a separate copy of the spool directory initialized by postfix -c your_cfg_dir check after your_cfg_dir is ready.
  • Avoid letting mail to any dspam learning alias pass through content_filter. Trying to learn with dspam after the forwarded mail is processed again with dspam is guaranteed to break.

Feel .:: awesome
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