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Showing posts from November, 2008

Don't try this at home, folks!

bkil@work /home/bkil/1 $ tar --remove-files -cvzf 1.tar.gz .
./
./1.sh
./cp_ln.sh
./cp_ln.sh.
./format.mysql.txt
(...)
./test2.sh
./things_for_my_blog.tar.bz2
./wc-c
./wgetd.sh
./very_important_files.tar.bz2
./1.tar.gz
tar: ./1.tar.gz: file changed as we read it
tar: .: Cannot rmdir: Invalid argument
tar: Error exit delayed from previous errors

bkil@work /home/bkil/1 $ ls
bkil@work /home/bkil/1 $ ls -a
. ..
bkil@work /home/bkil/1 $

Thankfully, I could reconstruct every import file from my backups except for some uninteresting logs. I have compressed "." before, and I have also used the "--remove-files" switch many times, but it looks like I rarely combine the two. Now I remember why! :) I should have written either "cd ..&&tar --remove-files -cvzf 1.tar.gz 1" or "tar --remove-files -cvzf 1.tar.gz * .[^.]* ..?*"

Riding your bike compared to using local public transport

Advantages
* no waiting time at stops or changes - direct and dedicated connection (see note#1)
* no idling at intermediate stops - rapid transit
* stops are at your doorsteps - no walking that slows you down
* traffic congestion is usually not a problem
* never crowded, you always have a seat
* the air conditioning is always on and works as you will
* fares are fair and mostly constant - doing some inexpensive maintenance once in a few months or twice a year
* about the same journey time overall as on bus or tram - some routes are even faster
* exercise is good for you
* lower top speed - safer

Drawbacks
* you can't read a newspaper and such (except at traffic lights)
* in very bad wet weather you may have a hard time without full fairing
* bikes must face inferior road conditions on the side of the road and on unmaintained bike paths
* more traffic light waiting time on many routes
* lower top speed

Note #1: You may combine bicycle commuting with public transport if you have a portable bike. Thi…

NEWS: Horner oneliner in Haskell

It's fun that evaluating a polynomial using the Horner-scheme takes only a single line of Haskell code. I wish they had thought functional programming as a basic skill! ;)
http://people.inf.elte.hu/bkil/en/pg/horner.hs

They're using standard rail gauge in our capital city

We went to the Function demoparty organized at our capital city a few years ago with a friend of mine. He asked on the way to the party place on a HEV vehicle if they use standard rail gauge. I couldn't come up with a definite answer then, but I was pretty sure in that they use the 1,435 mm, so called 'Normal gauge'. This post has been written now because I have just recently bumped into that article.

Another interesting point is that the HEV is not light rail, but commuter rail instead.

MAV has been doing bridge reconstruction recently. While these works are underway, MAV vehicles use a section of the northern HEV line. See below for a few neat videos about this.
youtube: MAV on BKV HEV
youtube: MAV trains on HEV rails
youtube: Desiro to Margaret bridge
youtube: HEV&MAV trains

By the way, I'm still open to suggestions concerning my grammar and spelling. Please don't hesitate about either posting here or sending me mail! :)

NEWS: added quotes, updated Lenny instructions

I have added a few more insightful quotes. The Debian Lenny instructions got a slightly modified package list. I fixed a few minor bugs in the text while at it (ampersand missing and the like). Also added some sound related instructions.

Design a minimalistic font with grave discrepancy

My plan is to experiment with (monochromatic-) font designs. They would need to have a one-to-one correspondence with the Latin alphabet and Hindu-Arabic numerals. The object is to provide better clarity than the best possible with standard fonts. I will start investigating numerals first. It is a bonus if some symbols would resemble standard ones.

NEWS: summa v0.1, links

I have done minor refactoring on "summa.erl": abstracted seq/2 and reorganized maps into list comprehension.

Added links related to the firearm debate. Fixed some small distro related ones.

NEWS: ASCII v0.1.2, SI v0.1, working on bikes

I put some of my new drawings in the collection, so enjoy!

As I use the SI measure converter regularly, I have enhanced it's interface with the common function "convert". For example si:convert( 40,psi, bar) converts 40 psis into bars, or si:convert( 15,mph, kph) converts from miles per hour into kilometers per hour. si:convert(mph,kph) gives the scalar factor (1.6). Complex measures also work as usual, so you can query si:convert( {u,314,[ft,ft,lb],[s,s]}, {u,1,[n,m],[]} ).

A bicycle related post or two is in the works. They're almost ready to be more exact.

Loud networking with 2-AFSK

I wonder how far one could transmit using only sound waves in open air? I am considering something that would not be intrusive, so it needs to emit below the regulated acceptable ambient sound pressure limits (about 30-40dB here). I only intend to operate it intermittently, maybe for a few seconds in every hour - depending on attainable bandwidth. My ultimate goal is to be able to transfer about an SMS in a run, but I would be more than happy to make trade-offs that could result in quieter operation.

Higher frequency carriers could both provide more bandwidth easily and be inaudible at the same time, but there's a catch. They say, sound waves below about 1kHz usually penetrate air much better than ultrasounds. I need to test this specifically, but about at most 500Hz-1000Hz looks like a hard upper limit for long range transmission according to the graphs. Another drawback of larger wavelengths is the enormous sized dish that would be needed to concentrate the beam of sound. By the …