Geoff Knauth's Weblog

pilot-friendly iPads

2011-10-14T11:19:00.001-04:00

I made a spreadsheet of iPad versions for a CAP friend who found out, the hard way, that he'd bought the wrong iPad for flying purposes. He intended to buy an iPad with 3G capability, because [whether or not you activate 3G service], 3G models have a GPS receiver. But a BestBuy sales droid convinced him to buy a non-3G model and add a mifi device that connects to Verizon. While that can help you create a small (4-5 machine) slow-speed WiFi network in a place on the ground that doesn't have any WiFi, it does nothing for you in an airplane because most of the time you won't get cell tower signals. In an airplane, you need to receive signals from GPS satellites.

The issue of whether you can benefit from an additional GPS receiver with WAAS capability, either plugged into your iPad, or connecting through the air [short distance] via Bluetooth, is a separate issue. One friend has a Bluetooth GPS, I bought the plugin kind, and I may switch to the Bluetooth variety. The GPS inside my iPad works fine, but the extra receiver gives you better reliability and precision. The plugin kind gets power from your iPad but itself can be plugged in to your cockpit's cigarette lighter keeping your iPad charged; its main drawback is that you can't use it with a certain kind of knee strap. The Bluetooth kind needs to be charged before you fly.

Generate list of numbers 0..n-1 in randomized order using DrRacket

2011-08-07T15:10:00.001-04:00

The most fun was looking at shuffle-list.

Nice travel video about Kazakhstan

2011-07-04T08:21:00.001-04:00

Our fourth exchange student, Adil, who is coming from Almaty, Kazakhstan for the 2011-2012 school year, sent us this travel video made by a Russian videographer friend of his, Denis Matveev, who visited Kazakhstan in the summer of 2010. The video reminds me of Colorado, where I lived in 1972. Denis is creative and his other videos are good too. Take some time to browse his site; it will put a smile on your face.

Pain after macports "routine" MySQL/PHP update, now relieved

2010-02-02T14:23:00.007-05:00

I did a port selfupdate, and updated a few ports, then spent four hours underwater dealing with things that suddenly stopped working:

  php5 fatal error call to undefined function mysql_connect

Making sure I had the following installed (with options I needed) fixed the error above.

mysql5-server 5.1.42_0 (was already OK)
php5 5.3.1_1+apache2+darwin_10+fastcgi+macosx+mysql5+postgresql83+sqlite
php5-mysql 5.3.1_2+mysqlnd

I checked the setup with php_info(), but then I got another error:

  mysql_connect() [function.mysql-connect]: [2002] No such file or directory (trying to connect via unix:///tmp/mysql.sock)

After some investigation, I created a php.ini file:

$ sudo cp /opt/local/etc/php5/php.ini{-development,}
  $ sudo chown username /opt/local/etc/php5/php.ini

Edited php.ini:

< mysql.default_socket =
  --
  > mysql.default_socket = /opt/local/var/run/mysql5/mysqld.sock

(I have a memory of having done something like this before, but apparently I had to do it again.)

Then, of course, I got new errors:

mysql_connect() [function.mysql-connect]: OK packet 6 bytes shorter than expected.
  mysql_connect() [function.mysql-connect]: mysqlnd cannot connect to MySQL 4.1+ using old authentication in ...

The Google helpfully led me to this stackoverflow answer (why didn't I think of that first?!), and the answer was a total surprise. Happily, after the final fix, everything is working again:

mysql> select Length(`Password`), Substring(`Password`,1,1)
  from `mysql`.`user` where `user` = 'username';
  +--------------------+---------------------------+
  | Length(`Password`) | Substring(`Password`,1,1) |
  +--------------------+---------------------------+
  |                 16 | 3                         |
  |                 16 | 3                         |
  |                  0 |                           |
  +--------------------+---------------------------+
  3 rows in set (0.07 sec)
  mysql> set password for 'username'@'localhost' = PASSWORD('password');
  Query OK, 0 rows affected (0.00 sec)
  mysql> select Length(`Password`), Substring(`Password`,1,1)
  from `mysql`.`user` where `user` = 'username';
  +--------------------+---------------------------+
  | Length(`Password`) | Substring(`Password`,1,1) |
  +--------------------+---------------------------+
  |                 41 | *                         |
  |                 16 | 3                         |
  |                  0 |                           |
  +--------------------+---------------------------+
  3 rows in set (0.00 sec)

Now that a good chunk of my "free day" has been used up, I think I'm going outside for some fresh air.

Building ghc-6.12.1 on Novell SUSE GNU/Linux

2010-01-28T12:21:00.001-05:00

If you are building ghc-6.12.1 on Novell SUSE GNU/Linux, make install may fail with the message:

ghc.mk:95: Extraneous text after `else' directive
ghc.mk:96: Extraneous text after `else' directive
ghc.mk:96: *** only one `else' per conditional.  Stop

The solution is to install at least GNU make version 3.81.

Building PIL-1.1.6 on Mac OS X 10.6

2009-10-24T18:02:00.001-04:00

I was trying to get the Python Imaging Library installed on Snow Leopard. (This is for a "Python from python.org" environment separate from Apple standard and Macports.) I read a number of posts on the net, but it took a combination of ideas I found to arrive at a solution that worked.

Prerequisites: Install Xcode from the Snow Leopard disk. As you do that, make sure you check the box that enables continued 10.4 SDK support.

Then:

$ curl -O http://effbot.org/downloads/Imaging-1.1.6.tar.gz
$ tar zxf Imaging-1.1.6.tar.gz
$ sudo bash
# cd Imaging-1.1.6
# export ARCHFLAGS="-arch i686"
# export CFLAGS="-arch i686"
# python setup.py build
# python setup.py install
# exit

I don't like the cheap trick ("sudo bash"), but I found I needed the ARCHFLAGS and CFLAGS settings for both the build and install steps.

See also Rich Atkinson's use of pip on his blog post. That might be all you need.

Unhappy with HealthAmerica

2009-07-08T21:31:00.001-04:00

I am very unhappy with HealthAmerica, our college's health insurance provider. Our son had an ingrown toenail and the toe was infected. He was in great pain and was treated in January. Then we were billed the full amount. HealthAmerica said this was not covered. They have gone out of their way to wiggle out of paying anything. We appealed, they sent it to their Complaint Committee, and the committee sent us a final letter denying coverage for the procedure ("You have exhausted your complaint rights"), saying that "routine foot care" is not covered. The letter says that by exception "Medically Necessary surgery for ingrown toenails" would be covered. They didn't judge the relief of our son's pain or infection to be medically necessary. If you ever want to get a parent mad, that's it!

Other than helping my friend Dr. Ogan Gurel with his 700 mile Walk for Healthcare, I've been too passive in the ongoing debate about health care reform. The arrogance of companies like HealthAmerica angers me. I must and I will write my congressman and senators and urge them to vote for solutions that regulate such corporations more strictly and give Americans a public health care option. I have no confidence that HealthAmerica would actually cover us if something more serious were to occur.

2000 cricket bats

2009-04-13T04:16:00.001-04:00

We have an exchange student, Rachu, staying with us from Chennai, India. He told us he regularly played cricket with his friends on the beach on Sunday mornings, along with thousands of others. On the morning of 26 DEC 2004, he and his friends did not play cricket, because they had to study for exams. That was the day of the tsunami. After it hit, Rachu said 2000 cricket bats washed ashore. Each cricket bat represents six players.

Apple/Allstate Did Not Make My Day

2008-11-18T17:27:00.004-05:00

I used to tell people, get AppleCare. Now I've found out when AppleCare is no help. I walked into my college office, and saw a pile of books sitting on my MacBook Pro's display. A bookshelf support gave way, and the books came tumbling down. AppleCare doesn't cover that, but they gleefully told me they could fix it for $1360.

The college where I work can't help pay for the damage. They have a deductible that far exceeds the amount I'm stuck with.

For a while Allstate (my homeowner's) held out hope that I'd get some reimbursement because the damage involved "a falling object." But they just called to say that since the object (falling books) did not fall out of the sky, I'm not covered.

The total was $1228.38. The one bright spot is that Leading Electronics did a first class job fixing my computer.

Falling Incomes

2008-03-14T06:33:00.003-04:00

Lou Dobbs talks about "The War on the Middle Class." That prompted me to look at my own income 1978-2008.

XO via Mac Parallels v3

2008-01-03T04:19:00.001-05:00

Wrote: Step by step instructions for getting XO emulation up on a Mac using Parallels v3.

DrScheme on OLPC XO

2008-01-01T10:44:00.000-05:00

My children got OLPC XOs for Christmas. The first request by son William (8) was that I put DrScheme on his XO. I tried a standard build and it almost worked, but for a few missing libraries. I got on the PLT horn and very quickly Matthew Flatt, Noel Welsh and Grant Rettke offered help. Mako Hill of OLPC and FSF also pitched in. Grant has created several images that work on the XO, all of which work well. Our next task is to put a wrapper on the image to make it an Activity we can post on the OLPC wiki.

Lisp and Robotics at JPL

2007-02-14T06:24:00.000-05:00

One of my robotics students found this great personal account on the web:

http://www.flownet.com/gat/jpl-lisp.html

He probably sent it to me because he thought, "Hey look what you can do with a 68HC11!" True enough. But I read the article for what it said about Lisp. I saw management give similar short shrift to Lisp at BBN, BAE Systems, SPAWAR and SFA. The stories are all too familiar.

The good news is that eventually the limited solutions that get foisted on developers (or managers) eventually die out, and the good ideas from long ago keep re-emerging. If you live long enough, you realize it's an endless cycle, like those old diagrams showing rainfall, oceans and streams, evaporation and clouds. It's up to you to decide whether developers or managers are the oceans or the clouds; both positions could be argued.

In the meantime, my hope for computer science grows when I see the brightest of the new generation pick up the torch.

Comair Flight 5191

2007-01-18T17:26:00.000-05:00

A friend sent me a link to a Fox News / AP story with excerpts of the crew conversation before takeoff. As I read the transcript, I kept thinking, "CRM! CRM!" CRM stands for Crew Resource Management, a discipline, particularly around critical phases of flight, that the airlines and other pilot organizations have been drilling into pilots for quite a few years now. I kept thinking, "Why are these guys, probably good guys, talking about all this non-flying stuff now?" And when I read the bit about a "flex takeoff" procedure that uses less than full power, I was floored. I had to wonder if a full power takeoff could have gotten them off that short runway OK. I don't know whether "flex takeoff" is just an airline procedure meant to save some money, or if it's an early morning procedure to reduce noise. After all that, taking off from a runway without runway lights and not bringing that up with the open control tower, seems like the last straw.

But I think I understand part of how this happened. In the transcript, the pilots discussed working hours and tight schedules, flying into a place, spending a maximum of ten hours in a hotel, and then flying out again. When you do that, you have no social life. I'm guessing the pilots' social life was in that cockpit. The cockpit provided a time and place for chit-chat that was otherwise lacking in their busy lives. Unfortunately it was not the place for such talk, particularly in a critical phase of flight. I'm hoping the airlines learn from this, and loosen the schedules of commercial and airline pilots, so that they have adequate time to do their socializing in their off-hours, and so that while in the cockpit they have a greater feeling, "OK, I've had my time off, now I'm at work, and I must give it my full attention."

Prof. Keith Decker, loosely coupled distributed autonomous systems

2006-06-24T06:26:00.000-04:00

While at BBN, I sometimes worked with the Cougaar team to explore distributed system design as it related to complex logistics problems. Since Hurricane Katrina, I've often wondered if Cougaar could be used to model disaster response in a real-time context. As a CAP responder, I also think about the use of computers to improve search & rescue activity.

Now along comes this ACM TechNews article, referencing Prof. Keith Decker's work on loosely coupled distributed autonomous systems. See also the Univ. of Delaware press release. I'm very glad to see that Prof. Decker is specifically working to improve the ability of organizations to adapt their plans successfully to real-time events (such as Katrina) and constraints (e.g., bureaucracy and physical limitations).

darwinports

2006-05-22T06:32:00.000-04:00

Recently on Mac OS X I've transitioned my Berkeley DB, Graphviz, Hugs, MySQL, Octave, Perl, PHP, PostgreSQL, Python, SBCL and TeX installations to the Darwinports port package management system. On the whole, maintenance has become easier.

list of discrete math applets

2006-03-29T11:32:00.000-05:00

Prof. Eileen Peluso at Lycoming College sent me this list of discrete math applets put together by Prof. Susanna Epp of DePaul University.

This came from an ACM SIGCSE 2006 workshop.

maybe I should switch to FreeBSD or ubuntu...

2006-03-28T05:43:00.000-05:00

I just upgraded one of my systems from FC4 to FC5. Now I can't login to the console except in failsafe mode. When I ssh into the system, I see:

$ ls
ls: error while loading shared libraries: librt.so.1: cannot open shared object file: No such file or directory

I figured out what was wrong today (5/22):

I had this in my ~/.bash_profile from some much earlier Java installation:

export LD_ASSUME_KERNEL=2.2.5

I commented out that line with LD_ASSUME_KERNEL, which apparently is no longer supported, and that fixed everything.

MacQTeX for online math quizzes

2006-03-27T15:52:00.000-05:00

Macquarie University in Sydney, Australia has created some neat software for doing math quizzes online using MacQTeX with embedded Javascript in PDFs.

After FC5 upgrade, yum update stopped working

2006-03-27T04:34:00.000-05:00

After I upgraded my GNU/Linux system from FC4 to FC5, yum update stopped working. This is now fixed.

yum couldn't find repositories, it couldn't read repomd.xml files, it really couldn't do anything at all. Firefox would load a repomd.xml off the net just fine, but wget would act as though the file didn't exist.

I traced the problem (in my case) to /etc/nsswitch.conf:

< hosts: files nisplus dns
--
> hosts: files dns

Why this blog

2006-03-25T08:25:00.000-05:00

I started this blog so I could respond to something Mike Olson wrote at http://subclock.blogspot.com/2006/03/flat-is-new-open.html