Planet PLUG

Kyle Winfree: Gridding a Flash

Fri, 27 Jan 2012 04:56:44 +0000

I’ve been trying to learn more about my own photo gear lately, so that when ever an opportunity comes up, I will have the knowledge to put it to the best use. I bought some used flashed on ebay last month (see the post about the Sunpak 222 modification), and a simple grid off amazon. One flash I bought was a zoom flash (Sunpak 333). It has an integrated flash strength setting, thus doesn’t need the modification I made to the Sunpak 222s. So I wanted to know, does a grid make any difference on the zoom flash, and what are the differences between the 222 and the 333 in illumination area. Of course, this test is in no way perfect, but I did keep the camera settings for each exposure the same. The flash was placed about 1.25 meters from the wall.

Richard Freeman: rich0

Sat, 21 Jan 2012 21:28:36 +0000

Since the general trend on many linux distros is towards requiring /usr to be mounted at boot time, I figured I’d see what it would take to get it working using dracut.

I’ve been messing with dracut for a while, and for some reason it stubbornly refuses to detect my raid devices. The kernel autodetection works fine, but this is disabled when booting from an initramfs. Dracut would timeout and drop me to a dash shell, and if I just typed mdadm -As followed by exit it would boot just fine.

Dracut is using udev to set up raid devices, and obviously that is not working.

Beyond this, I’d like to get my /usr mounted pre-boot, and there is a module called usrmount that purports to do just this. However, it isn’t working in my case because /usr is a bind mount to a subdir on an lvm volume, and it just isn’t figuring that out (it doesn’t even run lvm in the first place despite having the module installed, let alone figuring out what to mount in what order – I suspect the lvm module only works if root is on lvm).

My solution to both problems is to build my own simple dracut module. If you want to try it out:

cd /usr/lib/dracut/modules.d/
mkdir 91local
cat > 91local/module-setup.sh
#!/bin/bash # -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*- # ex: ts=8 sw=4 sts=4 et filetype=sh

check() {
return 0
}

depends() {
return 0
}

install() {
inst_hook pre-trigger 91 "$moddir/mount-local.sh"
}

cat > 91local/mount-local.sh

#!/bin/sh

# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-

# ex: ts=8 sw=4 sts=4 et filetype=sh

mount_local()
{
mdadm -As
lvm pvscan
lvm vgscan
lvm lvscan
lvm vgchange -ay
}

mount_local

Then run dracut to build your initramfs, and it should let mdadm and lvm auto-detect everything before it gets to mounting stuff. You can then use the fstab-sys to mount whatever you need to mount user. However, in your fstab.sys if you’re configuring a bindmount be sure to prepend /sysroot/ before the source directory.
Example fstab.sys:
/dev/vg1/data /data ext4 noatime,user_xattr,barrier=1 0 0 /sysroot/data/usr /usr none bind 0 0 /sysroot/data/var /var none bind 0 0

Hopefully this helps somebody out – the dracut documentation is pretty sparse. In fact, if somebody connected to dracut stumbles upon this I’d be open to a better way of hooking my script – pre-trigger just doesn’t seem right – I’d rather let udev try to do everything first. However, I couldn’t find any way to hook after udev runs but before it bombs out not finding my root device. Suggestions welcome.

Filed under: gentoo, linux

mjd: Where should usage messages go?

Wed, 11 Jan 2012 13:06:00 +0000

Last week John Speno complained about Unix commands which, when used incorrectly, print usage messages to standard error instead of to standard output. The problem here is that if the usage message is long, it might scroll off the screen, and it's a pain when you try to pipe it through a pager with command | pager and discover that the usage output has gone to stderr, missed the pager, and scrolled off the screen anyway.

Countervailing against this, though, is the usual argument for stderr: if you had run the command in a pipeline, and it wrote its error output to stdout instead of to stderr, then the error message would have gotten lost, and would possibly have caused havoc further down the pipeline. I considered this argument to be the controlling one, but I ran a quick and informal survey to see if I was in the minority.

After 15 people had answered the survey, Ron Echeverri pointed out that although it makes sense for the usage message to go to stderr when the command is used erroneously, it also makes sense for it to go to stdout if the message is specifically requested, say by the addition of a --help flag, since in that case the message is not erroneous. So I added a second question to the survey to ask about where the message should go in such a case.

83 people answered the first question, "When a command is misused, should it deliver its usage message to standard output or to standard error?". 62 (75%) agreed that the message should go to stderr; 11 (13%) said it should go to stdout. 10 indicated that they preferred a more complicated policy, of which 4 were essentially (or exactly) what M. Echeverri suggested; this brings the total in favor of stderr to 66 (80%). The others were:

stdout, if it is a tty; stderr otherwise
stdout, if it is a pipe; stderr otherwise
A very long response that suggested syslog.
stderr, unless an empty stdout would cause problems
It depends, but the survey omitted the option of printing directly on the console
It depends

I think #2 must have been trying to articulate #1, but (a) got it backwards and (b) missed. #3 seemed to be answering a different question than the one that was asked; syslog may make sense for general diagnostics, but to use it for usage messages seems peculiar. #5 also seems strange to me, since my idea of "console" is the line printer hardwired to the back of the mainframe down in the machine room; I think the writer might have meant "terminal".

68 people answered the second question, "Where should the command send the output when the user specifically requests usage information?". (15 people took the survey before I added this question.) 50 (74%) said the output should go to stdout, 12 (18%) to the user's default pager and then to stdout, and 5 (7%) to stderr. One person (The same as #5 above) said "it depends".

Thanks to everyone who participated.

mjd: Elaborations of Russell's paradox

Tue, 10 Jan 2012 18:46:00 +0000

When Iris was five or six, I told her about Russell's paradox in the following form: in a certain library, some books are catalogs that contain lists of other books. For example, there is a catalog of all the books on the second floor, and a catalog of all the books about birds. Some catalogs might include themselves. For example, the catalog of all the books in the library certainly includes itself. Such catalogs have red covers; the other catalogs, which do not include themselves, such as the catalog of all the plays of Shakespeare, have blue covers. Now is there a catalog of all the catalogs with blue covers?

I wasn't sure she would get this, but it succeeded much better than I expected. After I prompted her to consider what color cover it would have, she thought it out, first ruling out one color, and then, when she got to the second color, she just started laughing.

A couple of days ago she asked me if I could think of anything that was like that but with three different colors. Put on the spot, I suggested she consider what would happen if there could be green catalogs that might or might not include themselves. This is somewhat interesting, because you now can have a catalog of all the blue catalogs; it can have a green cover. But I soon thought of a much better extension.

I gave it to Iris like this: say you have a catalog, let's call it X. If X mentions a catalog that mentions X, it has a gold stripe on the spine. Otherwise, it has a silver stripe. Now:

Could there be a red catalog with a gold stripe?
Could there be a red catalog with a silver stripe?
Could there be a blue catalog with a gold stripe?
Could there be a blue catalog with a silver stripe?

And more interesting:

Is there a catalog of all the catalogs with gold stripes?
Is there a catalog of all the catalogs with silver stripes?

I knew that early 20th century logicians, trying to repair the Russell paradox, first tried a very small patch: since comprehension over the predicate X∉X causes problems, just forbid that predicate. This unfortunately doesn't solve the problem at all; there are an infinite number of equally problematic predicates. (Whitehead and Russell's theory of types is an attempt to fix this; Quine's New Foundations is a different attempt.) One of these predicates is ¬∃Y.X∈Y and Y∈X. You can't construct the set of all X such that ¬∃Y.X∈Y and Y∈X because there is no such set, for reasons similar to the reason why there's no set of all X such that X∉X, so that's where I got the silver stripe predicate.

Translating this into barber language is left as an exercise for the reader.

mjd: Mental astronomical calculations

Thu, 05 Jan 2012 04:36:00 +0000

As you can see from the following graph, the daylight length starts increasing after the winter solstice (last week) but it does so quite slowly at first, picking up speed, and reaching a maximum rate of increase at the vernal equinox.

The other day I was musing on this, and it is a nice mental calculation to compute the rate of increase.

The day length is given by a sinusoid with amplitude that depends on your latitude (and also on the axial tilt of the Earth, which is a constant that we can disregard for this problem.) That is, it is a function of the form a + k sin 2πt/p, where a is the average day length (12 hours), k is the amplitude, p is the period, which is exactly one year, and t is amount of time since the vernal equinox. For Philadelphia, where I live, k is pretty close to 3 hours because the shortest day is about 3 hours shorter than average, and the longest day is about 3 hours longer than average. So we have:

day length = 12 hours + 3 hours · sin(2πt / 1 year)

Now let's compute the rate of change on the equinox. The derivative of the day length function is:

rate of change = 3h · (2π / 1y) · cos(2πt / 1y)

At the vernal equinox, t=0, and cos(…) = 1, so we have simply:

rate of change = 6πh / 1 year = 18.9 h / 365.25 days

The numerator and the denominator match pretty well. If you're in a hurry, you might say "Well, 360 = 18·20, so 365.25 / 18.9 is probably about 20," and you would be right. If you're in slightly less of a hurry, you might say "Well, 361 = 19², so 365.25 / 18.9 is pretty close to 19, maybe around 19.2." Then you'd be even righter.

So the change in day length around the equinox (in Philadelphia) is around 1/20 or 1/19 of an hour per day—three minutes, in other words.

The exact answer, which I just looked up, is 2m38s. Not too bad. Most of the error came from my estimation of k as 3h. I guessed that the sun had been going down around 4:30, as indeed it had—it had been going down around 4:40, so the correct value is not 3h but only 2h40m. Had I used the correct k, my final result would have been within a couple of seconds of the right answer.

Exercise: The full moon appears about the same size as a U.S. quarter (1 inch diameter circle) held nine feet away (!) and also the same size as the sun, as demonstrated by solar eclipses. The moon is a quarter million miles away and the sun is 93 million miles away. What is the actual diameter of the sun?

[ Addendum 20120104: An earlier version of this article falsely claimed that the full moon appears the same size as a quarter held at arm's length. This was a momentary brain fart, not a calculational error. Thanks to Eric Roode for pointing out this mistake. ]

mjd: η-reduction in Haskell and English

Tue, 03 Jan 2012 16:38:00 +0000

The other day Iris and I were putting together a model, and she asked what a certain small green part was for. I said "It's a thing for connecting a thing to another thing."

Iris objected that this was a completely unhelpful explanation, but I disagreed. I would have agreed that it was an excessively verbose explanation, but she didn't argue that point.

Later, it occurred to me that Haskell has a syntax for eliding unnecessary variables in cases like this. In Haskell, one can abbreviate the expression

        λx → λy → x + y

to just (+). (Perl users may find it helpful to know that the Perl equivalent of the expression above is sub { my ($x) = @_; return sub { my ($y) = @_; return $x + $y } }.) This is an example of a general transformation called η-reduction. In general, for any function f, λx → f x is a function that takes an argument x and returns f x. But that's exactly what f does. So we can replace the longer version with the shorter version, and that's η-reduction, or we can go the other way, which is η-expansion.

Anyway, once I thought of this it occurred to me that, just like the longer expression could be reduced to (+), my original explanation that the small green part was "a thing for connecting a thing to another thing" could be η-reduced to "a connector".

Perhaps if I had said that in the first place Iris would not have complained.

Happy new year, all readers.

Kyle Winfree: Pooled Standard Deviation and Principal Component Analysis

Mon, 02 Jan 2012 16:30:49 +0000

I just sent off my pca and poolstd functions to Octave-Forge for review. Here’s to hoping for success in them getting add to the stats package.

Kyle Winfree: Sunpak 222 Modification – Variable Flash

Sun, 25 Dec 2011 03:44:08 +0000

I’m getting back into photography, which is great and fun, except that it isn’t necessarily a cheap hobby. Luckily, I have some existing equipment that I can put to good use. One piece, that my mother in law gave to me years ago, is an old Sunpak 222 Auto Thyristor flash. This handy little flash has three settings (though it claims four). First, it can be set to flash at full power. Next, it can flash at some fairly low power. Finally, it can use the photosensor on the front to regulate when a thryristor is to stop flash output. This is handy for older cameras, as you can simply set the camera in manual mode to a specific shutter speed and f-stop according to the distance to the subject. The flash simply ramps up in intensity until enough light is detected by the small photosensor. This doesn’t work so well for my applications though. I’m using this flash off camera. Triggering is done by a set of PT-04 wireless (433 Mhz) triggers I got on ebay from China. These are NOT ttl, but then again they don’t need to be. I do however want to have some real control over the intensity of flash the Sunpaks provide. I came across a post on Flickr detailing how to modify another flash to enable variable output. So, with the help of rudy__ (http://www.flickr.com/photos/26197573@N07/), I found a suitable logarithmic 50 kohm potentiometer on Digi-Key (P3F6503-ND). Here’s a before a after picture showing how this potentiometer fits right into the flash without much modification. If you repeat this, you will need a 21/64 inch drill bit (actually an 11/32 might work better). I now have three of these with equally as many remote triggers, which I have already used for several shoots.

For a better description of how the photosensor and thyristor work together, see http://www.mts.net/~wrpa/Quench.html.

Richard Freeman: rich0

Wed, 14 Dec 2011 15:06:56 +0000

Agreeing with some advice on gentoo-dev, I’m going to post this as a blog entry instead of a Gentoo news item. The quick version of this update is expect to see 0.24.1 in portage in a few days. The long version follows…

As many have noticed, the Gentoo version of MythTV has been significantly lagging the upstream version. We plan to introduce 0.24.1, which is the current upstream stable version, in the next few days. Before going through the upgrade we wanted to make you aware of our future plans for MythTV in Gentoo and some of your alternatives.

The Gentoo MythTV package will generally try to stay closer to upstream than it has in the last year, but probably will only be updated a few times per year at most. It will benefit from the full Gentoo QA process, including introduction to ~arch followed by stabilization. Dependencies will also be controlled in line with Gentoo QA so things should suddenly not stop working without warning. Versions that are stabilized will stay in the tree longer after they are superseded for those who want to take their time with upgrades.

The versions of MythTV in Gentoo may also not support the full range of upstream plugins.

There is an alternative for those of you who want a more bleeding-edge experience. Upstream maintains a Gentoo overlay at: git://github.com/MythTV/packaging.git

The upstream repository will be the first to receive updates and will have many more intermediate versions including bugfixes. The overlay also supports all the upstream plugins. However, it is not subject to Gentoo QA policy – dependencies could stop working or disappear without warning, and older versions may not be kept around. Generally speaking, we have not heard complaints from those who use it. Any issues with the upstream overlay should be reported to the MythTV project and not to Gentoo bugzilla.

If you’re already using the upstream overlay you shouldn’t be impacted by anything done in Portage – your versions will generally stay higher than our own.

If we drop your favorite plugin and you want it back and are willing to help maintain it, send us a note at mythtv@gentoo.org. If you’re willing to test it and ensure it works for everybody else, we can keep it in the portage tree.

Filed under: foss, gentoo, linux, mythtv

mjd: Arithmetic expressions in shell scripts

Wed, 16 Nov 2011 21:20:00 +0000

This spring will be the 25th anniversary of my involvement with Unix, and I have spent way too much of that time writing shell scripts. Back before we had Perl and the other 'P' languages (Python, PHP, Puby, and Pickle) you programmed in C or you programmed in shell. Bourne shell, to be specific. (It was named for its author, Steven Bourne. There was a time before there was a Bourne shell, when there was only "the shell", written by Ken Thompson, but that predates even my experience.) People did sometimes try to program the C shell, but only the very foolish tried it more than once. (Tom Christiansen once wrote a very detailed article explaining why, if you are interested.)

C is still used, but it is still C, and, as they say, C is a language that combines the power of raw assembly with the expressiveness of raw assembly. If you wanted to do systems programming, you wrote in C, because that was what there was, but if you wanted to do almost anything else, you wrote in Bourne shell, because otherwise you spent a lot of time counting bytes and groveling over core dumps. If you knew what you were doing, you wrote as much as possible in Bourne shell, and for the parts where your shell script needed to do something interesting, you had it invoke some small utility program that you or someone else had written in C.

"Interesting" in this case had an extremely low threshhold. You called out to a C utility to sort data. You called out to a C utility to remove or rename a file. You called out to a C utility to test for the existence of a file. You called out to a C utility to compare two strings. In early versions of the shell, you called out to a C utility to perform file globbing—that is, to expand something like dir?/*.c to a list of files—although this function had been absorbed into the shell itself by 1979, several years before I arrived. You called out to a C utility to print a string to the terminal. And you called out to a C utility if you wanted to do arithmetic.

Even including languages that nobody is expected to actually use, Bourne shell is probably the only programming language I have ever used that does not have any built-in operators for performing arithmetic. Instead, there is a C utility program called expr which interprets its command-line arguments as an arithmetic expression, evaluates the expression, and prints the result on the standard output. So for example, if your script has variables x and y and you want to add these and store the result into z, you write:

       z=`expr $x + $y`

This will fork a subprocess, which will execute the command expr 3 + 4 (or whatever). The command will emit the string 7 into a pipe, and the shell will read the string out of the pipe and store it into z. Astounding!

The expr program is a real piece of crap. The following reasonable-seeming invocations of expr all fail:

       z=`expr $x + 1.5`
       z=`expr $x+$y`
       z=`expr $x * $y`

The first fails because the craptastic yacc parser in expr has a value stack that is integer-only, so the program was not written to handle fractional values, and will instantly abort with the message non-numeric argument upon encountering the string 1.5 in the input. The second fails because the craptastrophic lexer (a whole 12 lines of C code) assumes that each command argument will be a single token, and makes no effort to actually do any, you know, lexing. The third fails because expr is a command run in a subshell, and since the * character is special in the shell it expands to a list of the files in the current directory, so although you thought you were going to run expr 3 * 4 you actually ran expr 3 hostid sys3 sys3.tar.gz v5root v5root.tar.gz v6doc v6doc.tar.gz v6root v6root.tar.gz v6src v6src.tar.gz v7 v7.tar.gz 4. The whole thing is a craptaclysm of craptitude.

A better way to do arithmetic in a shell script was to invoke a different utility program, bc, the "basic calculator". You sent your arithmetic expression to bc on the standard input (which avoided the craptysmal shell expansion of *) and got the answer on the standard output, typically something like this:

    z=`echo "$x + $y" | bc -l`

You needed the -l flag to enable floating-point calculations; it also enabled certain higher functions such as square roots and trigonometry.

I had assumed that bc was a later development than expr, but it appeared in Unix version 6, while expr did not appear until version 7. So then I thought perhaps expr had been thrown in as a demonstration of yacc, but no, yacc was already present in version 5, and anyway, bc was written with yacc. So I no longer have any workable theory about who perpetrated expr, or why. (I have emailed Brian Kernighan to ask, and if he says anything interesting I will post an addendum.)

Anyway, about ten years after all this, the GNU project was in full swing and was reimplementing all the standard Unix tools, including the shell. Since they wanted their implementations to displace the standard implementations, they added all sorts of bells and whistles to them. So their shell, bash, contained all sorts of stuff. Among other things, it had built-in arithmetic. In bash, if you want to add x and y and put the result into z you can write:

    z=$(( x + y ))

or even:

    z=$((x+y))

The nifty $(( punctuation was necessary because the syntax had to be backward compatible with the Bourne shell, and every clean syntax was already used for something else. The $((…)) feature was a great improvement over expr, and in some ways, it was even an improvement over bc. It is much faster, for one thing. And since it does not invoke a subshell, you don't have to worry about * doing something weird.

But in other ways it was a step backwards. It does not have any of bc's higher mathematical functions. It doesn't do radix conversion. And it does all its calculation in machine integers, so not only does it fall short of bc's arbitrary-precision arithmetic, it can't even handle fractions:

	x=3; y=4.5
	echo $((x+y))
	     bash: 4.5: syntax error: invalid arithmetic operator (error token is ".5")

Why? Why why why??? Who ordered that? I mean, I hate floating-point arithmetic as much as the next guy—probably more—but even I recognize that people need to do it sometimes.

Well, here we are, eleven hundred words into this article and I have still not come to the point. That is typical for me, but I think that contrary to my usual practice, I will cut the scroll here and get to the real point in a day or two.

Richard Freeman: rich0

Sat, 12 Nov 2011 02:45:16 +0000

I’ve been trying to learn a little more about kernel debugging (part of my quest to learn a little more about btrfs), and I figured I’d post a quick howto on getting kernel crash dumps captured on Gentoo.

Certainly a more elegant solution than this could be devised with more automation. It wouldn’t take much to setup, and turning it into a package might be nice. Maybe a project for the future if I manage to generate enough panics.

There are a lot of posts about kdump you’ll find on Google, but most are distro-specific and leave out how to actually make it work if it isn’t already configured. The best post I’ve found is this one, which this procedure is largely based on.

To keep things simple I’m going to just use a single kernel for the system and recovery, which creates just a few limitations on your kernel configuration.

emerge kexec-tools – you won’t get anywhere without this.
Check your kernel configuration for the following settings:
CONFIG_KEXEC=y CONFIG_SYSFS=y CONFIG_DEBUG_INFO=Y(technically not needed, but what’s the point)CONFIG_CRASH_DUMP=y CONFIG_PROC_VMCORE=y CONFIG_RELOCATABLE=y
Edit your grub.conf and add to your boot line crashkernel=64M for up to around 12GB of system RAM
Create /etc/local.d/kdump.start containing (don’t forget to chmod it a+x):
#!/bin/bash

kexec -p /[path-to-kernel] --append="root=[root-device] single irqpoll maxcpus=1 reset_devices"

That’s it. Note that your kernel has to be reachable, and the typical gentoo config leaves /boot unmounted, so you’ll either need to remove noauto from your fstab or place a copy of your kernel elsewhere.

I didn’t get this working with an initramfs – this is supposed to be possible but obviously the more complexity the trickier.

With these changes whenever you get a kernel panic or lockup (hard/soft if the kernel is set to detect them) the system will use kexec to run the kernel in crash mode, relocated to a reserved area of memory. The rest of RAM will be untouched. When the system boots up log in and copy /proc/vmcore to a file – this is your crash dump. Then reboot your system to get back to a normal configuration – you shouldn’t continue to operate in this state.

The obvious improvement to this is to create a script and run it with init= and have it copy the core file for you, then reboot…

Filed under: gentoo, linux

Kyle Winfree: RMS to visit UDel

Wed, 09 Nov 2011 16:31:21 +0000

You can find more information at https://crm.fsf.org/civicrm/profile/create?gid=41&reset=1 and http://sepp.udel.edu

Kyle Winfree

Wed, 09 Nov 2011 02:08:32 +0000

I think I know some people who can relate to this. Well done xkcd.

mikegrb: Devops w/ Perl @ Linode PPW Talk Slides

Thu, 27 Oct 2011 18:46:31 +0000

Earlier this month a gave a talk about Linode’s use of Perl for devopsy things at the Pittsburgh Perl Workshop. Finally getting around to posting the slides online. I wanted to add some details so more of the slides made since on their own but haven’t gotten around to it yet.

DevOps w/ Perl @ Linode.pdf (2.1MB)

Kyle Winfree: Thanks to our township!

Tue, 18 Oct 2011 13:19:07 +0000

Kyle Winfree: Pollo Santa Clara

Mon, 10 Oct 2011 21:24:28 +0000

Dinner at a Cuban restaurant in the Miami airport, Ku-va. Very good, even the plantains.

Kyle Winfree: Running PSPP Alpha 0.7.8

Thu, 06 Oct 2011 12:46:26 +0000

PSPP 0.7.8 adds a fair amount of functionality not available in 0.6.2. For example, it’s easy to export data into another (not PSPP/SPSS) format. Additionally, the output screen is much more graphically appealing, and allows for saving to several formats. These include text, post script, and pdf! But maybe the more important additions are the new analysis methods.

I had some issues installing, though it was easy to fix. In Mandriva 2011 or 2010.2, one also needs to install gettext and perl-devel. Just that simple.

Tharun Kumar Allu: Search and Replace large files inplace

noreply@blogger.com (Tharun) — Sat, 01 Oct 2011 15:04:20 +0000

using sed

find /path/to/files -type f -exec sed -i 's/fromString/toString/g' {} \;

using perl

find /path/to/files -type f -exec perl -pi -e  's/fromString/toString/g' {} \;

Kyle Winfree: FSF Blog

Tue, 20 Sep 2011 03:55:10 +0000

Sweet, some of my pictures made it to an FSF blog (very bottom of the page, 2011-04-20 University of Pennsylvania)

http://www.fsf.org/blogs/rms/a-selection-of-photographs-from-some-of-rmss-past-events

Kyle Winfree: GNU to the rescue again! PSPP instead of SPSS

Wed, 14 Sep 2011 02:16:10 +0000

The standard in my field for statistical analysis is SPSS, but I’m just not interested in getting locked into a contract. I’ve done that with other software in the past, and regretted it later when I wanted to regain access to an older file. So, this time I’m choosing to maintain my freedom to use the software as I wish, now and in the future.

For you other Mandriva 2010.2 Free i586 users:

$ sudo urpmi gcc

$ sudo urpmi libgsl-devel

$ sudo urpmi perl

$ sudo urpmi libplotutils-devel

$ sudo urpmi libgtk+2-devel (I went with libxrender-devel-0.9.6-0.1mdv2010.2.i586)

$ sudo urpmi libglade2.0_0-devel

$ sudo urpmi zlib

$ sudo urpmi libxml2

$ sudo urpmi libncurses5

$ sudo urpmi libreadline6

$ sudo urpmi texinfo

$ sudo urpmi libpq (I went with libpq8.4_5-8.4.7-0.1mdv2010.2.i586)

$ tar xvf pspp-0.6.2.tar.gz

$ cd pspp-0.6.2

$ ./configure (success!)

$ make

$ sudo make install

$ psppire (start the graphical interface)

PSPP Graphical Interface

GNU PSPP

How to compile pspp for Mandriva Linux

Kyle Winfree: My Stats Course Starts Monday

Fri, 09 Sep 2011 04:13:36 +0000

This seems fitting:

Credit to xkcd.com

mjd: Concerts

Sat, 27 Aug 2011 01:12:00 +0000

Order
Solving Mathematical Problems

with kickback
no kickback

At a book sale I recently picked up Terence Tao's little book on problem solving for 50¢. One of the exercises (pp. 85–86) is the following little charmer: There are six musicians who will play a series of concerts. At each concert, some of the musicians will be on stage and some will be in the audience. What is the fewest number of concerts that can be played to that each musician gets to see the each of the others play?

Obviously, no more than six concerts are required. (I have a new contribution to the long-debated meaning of the mathematical jargon term "obviously": if my six-year-old daughter could figure out the answer, so can you.) And an easy argument shows that four are necessary: let's say that when a musician views another, that is a "viewing event"; we need to arrange at least 5×6 = 30 viewing events. A concert that has p performers and 6-p in the audience arranges p(6 - p) events, which must be 5, 8, or 9. Three concerts yield no more than 27 events, which is insufficient. So there must be at least 4 concerts, and we may as well suppose that each concert has three musicians in the audience and three onstage, to maximize the number of events at 9·4 = 36. (It turns out there there is no solution otherwise, but that is a digression.)

Each musician must attend at least 2 concerts, or else they would see only 3 other musicians onstage. But 6 musicians attending 2 concerts each takes up all 12 audience spots, so every musician is at exactly 2 concerts. Each musician thus sees exactly six musicians onstage, and since five of them must be different, one is a repeat, and the viewing event is wasted. We knew there would be some waste, since there are 36 viewing avents available and only 30 can be useful, but now we know that each spectator wastes exactly one event.

A happy side effect of splitting the musicians evenly between the stage and the audience in every concert is that we can exploit the symmetry: if we have a solution to the problem, then we can obtain a dual solution by exchanging the performers and the audience in each concert. The conclusion of the previous paragraph is that in any solution, each spectator wastes exactly one event; the duality tells us that each performer is the subject of exactly one wasted event.

Now suppose the same two musicians, say A and B, perform together twice. We know that some spectator must see A twice; this spectator sees B twice also, this wasting two events. But each spectator wastes only one event. So no two musicians can share the stage twice; each two musicians share the stage exactly once. By duality, each two spectators are in the same audience together exactly once.

So we need to find four 3-sets of the elements { A, B, C, D, E, F }, with each element appearing in precisely two sets, and such that each two sets have exactly one element in common.

Or equivalently, we need to find four triangles in K₄, none of which share an edge.

The solution is not hard to find:

	1	2	3	4
On stage	A B C	C D E	E F A	B D F
In audience	D E F	A B F	B C D	A C E

And in fact this solution is essentially unique.

If you generalize these arguments to 2m musicians, you find that there is a lower bound of concerts, which is 4. And indeed, even with as few as 4 musicians, you still need four concerts. So it's tempting to wonder if 4 concerts is really sufficient for all even numbers of musicians. Consider 8 musicians, for example. You need 56 viewing events, but a concert with half the musicians onstage and half in the audience provides 16 events, so you might only need as few as 4 concerts to provide the necessary events.

The geometric formulation is that you want to find four disjoint K₄s in a K₄; or alternatively, you want to find four 4-element subsets of { 1,2,3,4,5,6,7,8 }, such that each element appears in exactly two sets and no two elements are in the same. There seemed to be no immediately obvious reason that this wouldn't work, and I spent a while tinkering around looking for a way to do it and didn't find one. Eventually I did an exhaustive search and discovered that it was impossible.

But the tinkering and the exhaustive search were a waste of time, because there is an obvious reason why it's impossible. As before, each musician must be in exactly two audiences, and can share audiences with each other musician at most once. But there are only 6 ways to be in two audiences, and 8 musicians, so some pair of musicians must be in precisely the same pair of audiences, this wastes too many viewing events, and so there's no solution. Whoops!

It's easy to find solutions for 8 musicians with 5 concerts, though. There is plenty of room to maneuver and you can just write one down off the top of your head. For example:

	1	2	3	4	5
On stage	E F G H	B C D H	A C D F G	A B D E G	A B C E F H
In audience	A B C D	A E F G	B E H	C F H	D G

Actually I didn't write this one down off the top of my head; I have a method that I'll describe in a future article. But this article has already taken me several weeks to get done, so I'll stop here for now.

[ Addendum: For n = 1…10 musicians, the least number of concerts required is 0, 2, 3, 4, 4, 4, 5, 5, 5, 5; beyond this, I only have bounds. ]

Walt Mankowski: "perl -00pe0" vs "cat -s"

Fri, 19 Aug 2011 02:36:00 +0000

I should have mentioned in my previous blog post that my friend Jonathan originally told me about perl -00pe0. After I posted it, we exchanged a few more emails about various ways to squeeze multiple blank lines, and he pointed out that cat -s is not, in fact, exactly the same as perl -00pe0. The difference is how they deal with leading blank lines. cat -s will squeeze them down to a single blank line, but perl -00pe0 will remove all of the leading blank lines.

Walt Mankowski: Perl one-liner to squeeze blank lines

Tue, 16 Aug 2011 02:58:00 +0000

I learned a fun new perl one-liner today:

perl -00pe0 foo >bar

What does it do? Well, it's nearly the same as cp foo bar, except that it squeezes multiple blank lines into foo into a single blank line in bar.

How does it do that? Well, let's break it down piece by piece. Perl's -0 flag lets you change perl's "input record separator". This lets you fiddle with perl's idea of what a "line" is. Normally perl reads in text a line at a time, where a "line" is a string of text terminated by a newline character. But when you set the -0 flag to 0, perl will keep reading until it hits a string of 2 or more newlines in a row. In other words, perl will read in text a paragraph at a time, and stop when it hits a blank line. If there are multiple blank lines, perl will treat them as if there was just a single blank line and throw away the extras. (You can also do the same thing by setting perl's special $/ variable to "".)

The next flag is -p. That tells perl to read in text a "line" at a time, execute some code against each line, and then print the line to standard output. Of course, because of the -00 right before it, each "line" is actually a paragraph.

The final flag is -e. This tells perl that the following parameter is a program that it should execute after it reads in each line. Normally this is given in between single quotes, but here the entire program is simply "0". This is a perl idiom for a no-op. This is because we don't need any additional code — the combination of the -00 and -p flags are all we need.

Incidentally, blank lines can be squeezed much simply, and with far less obfuscation, by running cat(1) with the -s flag:

cat -s foo bar

Kyle Winfree: New Tomatoes

Fri, 12 Aug 2011 02:59:53 +0000

It’s really pretty sad how we came by these. A good friend of ours lost her house to a fire. She was unable to keep her veggies at her interim rental, so she passed them along to us. They came with broken glass, but no heat damage.
We wish her the best as she recovers from her losses.

Kyle Winfree: There it is …

Mon, 08 Aug 2011 20:37:57 +0000

Some may say it’s silly, but still it’s kind of neat to think that I just downloaded my own code from a publicly reviewed software repository. I hope this is just the start (especially since I’ll be taking a stats course next semester).

repanova.m

Kyle Winfree: No Offense to the WYSIWYG Editor

Mon, 08 Aug 2011 19:22:28 +0000

But this is painful! Let me have my kwrite, vi, and latex at the command line. Seriously, I’m just working on a 30ish page document, and wondering how anyone can do something like a thesis/dissertation in Word (or even Open Office). Repetitive button clicking – bad, cascading markup – good.

Kyle Winfree: Tomato update

Sun, 07 Aug 2011 18:56:04 +0000

I think theres a few hundred green tomatoes on the eight vines.

Kyle Winfree: “When Patents Attack!” A Must Listen Podcast!

Wed, 03 Aug 2011 14:53:27 +0000

Those of you who know me well, know that I really enjoy This American Life and Planet Money. After a week+ away from my podcast list, I finally had a chance to listen to the TAL story on patents from July 22, 2011. It’s a must listen for anyone concerned about intellectual property, or even for that matter, anyone who cares to think about what’s included in the cost of buying technology. Did you ever think about the patents for your iPhone? How much do you pay in to ensure the company has the freedom to do what ever they want with the patent? Who has to pay off who? Anyway, check it out. Just as well, there is a Planet Money podcast on the same topic, also worth listening to.

http://www.thisamericanlife.org/radio-archives/episode/441/when-patents-attack

http://www.npr.org/blogs/money/2011/08/02/138934689/the-tuesday-podcast-the-patent-war

Kyle Winfree: Octave Function Accepted – repanova.m

Fri, 29 Jul 2011 13:38:25 +0000

I just got word that my repeated measures ANOVA function has been accepted to Octave-Forge and that it will be part of the next release.

Kyle Winfree: Decoding ASK RF Signals by Hand – Filling in Zero Space

Tue, 26 Jul 2011 06:34:06 +0000

My first radio listener for the weather station project was able to determine the order and duration of ones, but it didn’t tell much of a story about the zeros. I’ve just uploaded a sketch and the accompanying Octave script to record and display the signal with zeros space filled in. This being said though, I don’t yet have a good grasp on how many zeros might exist between ones, nor do I know how this signal changes with soil moisture or temperature, but I’m getting there.

Kyle Winfree: FOSSCON 2011 – that was fun

Sat, 23 Jul 2011 20:41:01 +0000

While I had to leave before it came to completion, I’m glad I made it to FOSSCON this year. Elizabeth Krumbach gave a good intro talk on contributing to FOSS projects, Mark Dominus presented a very engaging talk on git – ad-hoc style, and Robert Blackwell’s talk on interfacing Arduino nicely painted the scene for real world computer I/O using Arduino – like an email service connected to a door bell. I wasn’t able to see all the talks (like the second session that ran concurrently to the first), but all-in-all I think it went well.

Kyle Winfree: FOSSCON 2011

Sat, 23 Jul 2011 12:10:02 +0000

I’m headed into the city for FOSSCON 2011; I’m pretty excited to attend this, as I simply didn’t have access to such events in AZ. I think I’m most looking forward to the talk on using perl to communicate with Arduino.

Kyle Winfree: Getting Started on an Arduino Based Weather Station

Thu, 21 Jul 2011 20:15:14 +0000

Okay, so there are plenty of weather stations available for purchase, but so few are either a) inexpensive or b) interface several sensors the way I would like to see it done. So here’s my plan: I will use an Arduino and the related hardware to create a web device that posts current indoor and outdoor temperature and humidity. It will also provide outdoor wind speed and soil moisture level. This web device will connect to my web server to provide weather logging, and eventually weather forecasting. Of course, what I would really like to do, once I can tap into the thermostat of my own house, is use the forecasting and current information to control the air conditioner and heater. Take it a step further, and I should be able to adjust my desired indoor temperature via a secured web page.

I’m keeping a diary of the project, in hopes that it will help others who are trying to interface undocumented 433MHz RF equipment with an Arduino. That page can be found here.

Kyle Winfree: Another try at contributing to Octave

Thu, 21 Jul 2011 19:08:36 +0000

A year ago I tried to contribute a Gramian function to Octave Forge. As it turned out, there really wasn’t much need for it (at least not without adding functionality beyond the basic definition of the Gramian). Since then though, I’ve come across something missing in both Matlab and Octave that I’ve been using on a regular basis for my own purposes. This, is a Repeated Measures ANOVA function. So, I just sent off a patch to Søren.

In case you’re curious, my gramian.m function is available on my software page.

Kyle Winfree: Wednesday’s yield

Thu, 21 Jul 2011 13:27:10 +0000

This is the most we’ve gotten from our Sun Gold tomato plants thus far, but I would like to think this will end up being a trend. As of last estimate, we have about 320 green grape sized tomatoes that we should expect to be ripening soon.

Richard Freeman: rich0

Tue, 19 Jul 2011 20:24:24 +0000

If you haven’t noticed on gentoo-nfp, I’ve created an activity tracking page (with the help of David Abbot) to track periodic compliance activities for the Foundation.

Some have asked why do this, and why not simply use the Gentoo Calendar/etc to accomplish this?

My thinking is that the current tools do not go far enough. When the whole fiasco on the list about tax documents broke out a few months ago I started reading up and took more of an interest in these matters. What I’ve found is that truly staying on top of these kinds of activities involves a decent learning curve and quite a bit of organization. Even big corporations like Microsoft have let domains expire/etc. There are some activities that are just too important to allow to get lost in the shuffle.

My goal is for the activity tracker to turn into a one-stop-shop for any kind of recurring activity that the Foundation has to perform either due to strict regulatory compliance (like filing our taxes), or because it is just REALLY important (like renewing our domain name – though the scope of responsibility on that one is unclear to me).

The site is not going to be about work-in-progress or any kind of one-time events. I think that Bugzilla already is working fine for this. In fact, ideally I’d anticipate that any recurring activity like a tax filing would be associated with a series of bugs for each time it was performed.

Suggestions from the community are of course welcome. As anybody can see it is clearly a work in progress. However, I envision a day not long in the future where anybody can see an index of things that need to be done, when they need to be done next, and links to detailed pages on how to do them, and the results of having done them in the past. A volunteer wanting to take on some filing would be able to quickly learn everything they need to do it efficiently, freeing up Officers to supervise more. Or, when Officers do perform the work it will be done more consistently with fewer omissions, and links to tools, templates, and related materials will speed up the work.

And for the record, I think the volunteers managing the Foundation in the past few years have been doing a good job. This is hard work, and in any distributed organization staying on top of this is harder. In many cases they’ve inherited a bit of a mess and are doing their best to clean it up. The goal here is to make our problems and their solutions more transparent to all.

Once we’re done any concerned member of the community should be able to go down the list and audit us (well, to the extent we’re able to divulge things). If somebody notices a date coming up and no bug filed, they can file a bug or ping a trustee to make sure we’re doing our job. Sure, it might result in occasional embarrassment, but better that than serious non-compliance.

Filed under: gentoo, gentoo foundation

Kyle Winfree: First cucumber to amount to something.

Sat, 16 Jul 2011 23:21:49 +0000

I moved it off the ground so the bugs are less likely to eat it. It’s nice to see out doing so well…

Kyle Winfree: Matlab/Octave Repeated Measures ANOVA

Thu, 14 Jul 2011 07:40:57 +0000

Since I couldn’t find an officially supported function for repeated measures ANOVA either for Matlab or Octave, I resurrected one that I wrote in January. Now that it appears to be functional to my expectations, I think I’m going to take another stab at contributing something to Octave. Whether it’s accepted or not, I’ll post the function to my software page, which reminds me, I should add my overly simple Gramian function.

Kam Salisbury: Add the Virtualbox Yum Repo

kamreefsalisbury@gmail.com (Kam Salisbury) — Wed, 13 Jul 2011 11:18:11 +0000

Many Open Source applications are adding yum repositories in addition to providing rpm downloads! Starting with revision 3.x.x, Virtualbox has a repo file provided for easy download. Look at http://www.virtualbox.org/wiki/Linux_Downloads towards the bottom of the page.

Kyle Winfree: Arduino and Android using Amarino on an Archos

Wed, 13 Jul 2011 04:21:00 +0000

So I’ve been working with XBees for communicating between some custom Arduino hardware and a notebook computer, which has worked great, but the project has matured to the point where I would like to replace the notebook computer with either a tablet or smart phone (both running Android 2.2). There is, what looks to me to be at least, a nice package to facilitate exactly this kind of communication: Amarino. Though there are some really good tutorials out there, I thought I would add yet another (also to serve as a reference for myself when I’m setting up my programming environment on other computers).

To get started, and be able to do something useful later too, one should first install the Arduino development environment. You can get it here from the Arduino Download site. Though the Arduino environment is included in the PowerPack edition of Mandriva Linux, I prefer to use the latest version. In Mandriva though, you will need to install the AVR tools: avr-libc, avrdude, cross-avr-binutils, cross-avr-gcc, cross-avr-gcc-c++, and cross-avr-gcc-cpp. I like to extract the tgz to /usr/local/arduino-00xx. I haven’t yet figured out how to get it behave with rxtx communication without running as root, so I always run it with:

$sudo /usr/local/arduino-0022/arduino

You will also need to add the MeetArduino library to the libraries folder in Arduino. Simply copy the content into /usr/local/arduino-0022/libraries/MeetAndroid/. After verifying that the development environment can talk to your Ardunio hardware, upload the SensorGraphTutorial sketch. Though several sources suggest using a slower baud rate, I set mine to 115200 baud. This sketch then looks like:

/*
Sends sensor data to Arduino
(needs SensorGraph and Amarino app installed and running on Android)
*/

#include <MeetAndroid.h>

MeetAndroid meetAndroid;
int sensor = 0;

void setup()
{
// use the baud rate your bluetooth module is configured to
// not all baud rates are working well, i.e. ATMEGA168 works best with 57600
Serial.begin(115200);

// we initialize analog pin 5 as an input pin
pinMode(sensor, INPUT);
}

void loop()
{
meetAndroid.receive(); // you need to keep this in your loop() to receive events

// read input pin and send result to Android
meetAndroid.send(analogRead(sensor));

// add a little delay otherwise the phone is pretty busy
delay(100);
}

Next you should set up the Android development kit. I use Eclipse (like most people I assume). The kit can be found on the developers website. Rather than repeating what I think are really good directions, I’ll reference the installation instructions and note what extras I had to do in Mandriva. Since this project is for real devices, see those instructions. With the Archos 101 generation 8 tablet I have,my rules look like this:

$ cat /etc/udev/rules.d/51-android.rules
SUBSYSTEM==”usb”, ENV{DEVTYPE}==”usb_device”, ENV{PRODUCT}==”e79/*”, MODE=”0666″
SUBSYSTEM==”usb”, SYSFS{idVendor}==”e79″, MODE=”0666″

And my ~/.android/adb_usb.ini looks like this:

$ cat ~/.android/adb_usb.ini
# ANDROID 3RD PARTY USB VENDOR ID LIST — DO NOT EDIT.
# USE ‘android update adb’ TO GENERATE.
# 1 USB VENDOR ID PER LINE.
0×0e79

Of course, it says right here that you should not edit that file manually, but I found it was the only way to get my tablet to show up in the listed devices after:

$ adb kill-server
$ adb start-sserver
$ adb devices

Now if Eclipse is set up as per the instructions, and the adb server is recognizing the phone/tablet, you can (for this simple get-it-running example) install the Amarino Android App:

$adb install Amarino_2_v0_55.apk

Assuming the Amarino apk is in the current directory. At this point, the best thing to do is follow the Getting Started directions on the Amarino website. It’s at this point that I would like to point out that Amarino is a Free Software project (though I don’t think there is any support from FSF other than the GPL license). It’s listed as licensed under the GNU General Public License v3. As such, I’ll be using this to take my project forward!

/*
Sends sensor data to Arduino
(needs SensorGraph and Amarino app installed and running on Android)
*/

#include <MeetAndroid.h>

MeetAndroid meetAndroid;
int sensor = 0;

void setup()
{
// use the baud rate your bluetooth module is configured to
// not all baud rates are working well, i.e. ATMEGA168 works best with 57600
Serial.begin(115200);

// we initialize analog pin 5 as an input pin
pinMode(sensor, INPUT);
}

void loop()
{
meetAndroid.receive(); // you need to keep this in your loop() to receive events

// read input pin and send result to Android
meetAndroid.send(analogRead(sensor));

// add a little delay otherwise the phone is pretty busy
delay(100);
}

Kam Salisbury: Linux missing from MS ICTP

kamreefsalisbury@gmail.com (Kam Salisbury) — Wed, 13 Jul 2011 02:46:09 +0000

From tech , I had to add Linux+ since it was curiously missing from the official path of knowledge.

Kyle Winfree: The cucumbers outgrew the first trellis.

Sat, 09 Jul 2011 21:39:24 +0000

I was warned, so I should have known, but thats okay.

Kyle Winfree: Yes, the corn really is taller than the door.

Sat, 09 Jul 2011 21:37:24 +0000

I didn’t expect the corn to be quite so fast here (a opposed to in the front where it would get full sun), but I won’t complain.

Kyle Winfree: Harvesting sun gold tomato seeds.

Sat, 09 Jul 2011 13:19:15 +0000

Because we all like the sun gold tomatoes so much, I figured I would try harvesting some seeds from the defect tomatoes. The defect fruits I used had split on the vine while we were away. I think they split because of the watering system I put in; they got more water while we were away than before we left. So I don’t think they are really defective fruits, they just went through a rough transition in water supply. Anyway, heres my attempt following the directions outlined in this link from Jamie: http://www.youtube.com/watch?v=L_Yncr8rTfc

mjd: Longshot bets by time travelers

Thu, 07 Jul 2011 21:57:00 +0000

Back in February 2007, I started a blog article that was to begin as follows:

If you're a time traveller, one way to make money is by placing bets on events that you already know the outcomes of. The stock market is only the most obvious example of this; who wouldn't have liked to have invested in IBM in 1916?
But if making money is only your secondary goal, and your real object is to amaze your friends and confound your enemies, there may be more effective bets to place. I forget who it was who suggested to me how much fun it would be to go back to 1980 and bet that the cross-dressing star of Bosom Buddies would win back-to-back "Best Actor" Oscars within twenty years. But it's a fine idea.

I never finished this article, and I no longer remember where I planned to take it from there. I think I probably abandoned it because I realized that nothing else I could say would be as interesting as the Bosom Buddies thing. I don't think I could think of any examples that were less likely-seeming.

Until today. I wonder what sort of odds you could have gotten in 1995 betting that within twenty years, the creators of "What Would Brian Boitano Do" ("Dude! Don't say 'pigfucker' in front of Jesus!") would win the Tony Award for "Best Musical".

mjd: Watch out for the Calendar Geeks

Thu, 07 Jul 2011 21:57:00 +0000

Yesterday on the private IRC server run by my employer, one of my co-workers said:

<MHO> [My wife] just informed me that this year, July has five Fridays, five Saturdays and five Sundays. This only happens every 800 or so years.
<MHO> Calendar geeks, rejoice!

He made the mistake of invoking the Calendar Geeks, so here I am, ready to assist!

First, I note that any weird calendar event that occurs, will recur in no more than 400 years, because the Gregorian calendar repeats in a 400-year cycle and 400 Gregorian years is also an exact multiple of 7 days. (It is 400·365 days + (100 - 4 + 1) leap days = 146,097 days, which is exactly 20,871 weeks.) So it is impossible that the event could be as rare as once every 800 or so years. If it happens in 2011, then it happened in 1611 (in Catholic countries) and it will happen in 2411 also.

Now in the particular case cited by MHO, it's clear that since the length of July doesn't vary, the number of Fridays, Saturdays or Sundays depends only on the day of the week on which July 1 falls. You get five Fridays, Saturdays, and Sundays whenever July 1 falls on a Friday. Common sense suggests that this should happen about 1/7 of the time, and so around every 7 years, not every 800, or even every 400 years. And in fact it last occurred in 2005, and will occur next in 2016.

[ Addendum 20110527: It turns out this is actually a Thing; there is even a Snopes page about it. People will tweet almost anything, it seems. ]

[ Addendum 20110701: Matt Parker posted an extensive article about why he found this particular non-fact so dismaying. ]

Kyle Winfree: Gone for a week and a half and I couldn’t even walk into the garden…

Thu, 07 Jul 2011 01:11:17 +0000

The tomatoes really took off while we were gone. Those in the back are officially taller than me!

Kyle Winfree: Grandpa W’s Garden

Wed, 06 Jul 2011 03:02:31 +0000

My wife and I visited her grandparents in June/July. While there, her grandfather and I decided to put together a rain barrel with an automatic watering system. Our first try was with the barrel feeding a soaker hose. While water did leak out of the hose, it was clear that it wasn’t going to soak anything. So try two was a switch to using a drip irrigation system. This does work! Each tomato is watered every four hours for twenty minutes at a time at a rate of two gallons per hour. This adds up to 3.96 gallons per day per tomato plant, of rain water. The rhubarb is watered at half that rate, on the same schedule. This 104 gallon barrel then will only last about five days between fills, but hopefully most of the fills can be from rain water (the down spout will be connected at a later time).

Kyle Winfree: The third try, it’s a charm.

Mon, 27 Jun 2011 17:42:12 +0000

I should have started out leaving it outside….

Kyle Winfree: Homemade Dahi, Curd, Yogurt

Sun, 26 Jun 2011 03:41:40 +0000

This has been an interesting challenge to successfully go from milk to yogurt, but I think I’m finally there. I started this last night, still had milk this morning, then had really runny yogurt later in the day, and now, after adding more milk and keeping it all warm in a toaster oven, I think I have skim milk yogurt. I’ll use this culture to try again with whole milk tomorrow…

Kyle Winfree: Everyone likes automation

Sat, 25 Jun 2011 00:21:45 +0000

Now if I’m not around or forget, I won’t lose the tomatos because I forgot to water. And it was only $25!

Tharun Kumar Allu

noreply@blogger.com (Tharun) — Thu, 23 Jun 2011 17:04:02 +0000

Command to see CDP packets and identify the cisco switch and port your machine is connected to

# tcpdump -nn -vvv -i eth0 -s 1500 -c 1 'ether[20:2] == 0x2000'

Kyle Winfree: Green bean harvest

Sun, 19 Jun 2011 19:47:39 +0000

First harvest of beans and I don’t think they’ll even make it inside… Yum

Kyle Winfree: Tomatoes are coming in!

Sun, 19 Jun 2011 19:23:25 +0000

As you can see, the sun golds are starting to yield fruit.

Richard Freeman: rich0

Sun, 19 Jun 2011 02:59:05 +0000

I’ve gotten a few fair questions over the last few weeks about the status of MythTV on Gentoo. Here is a quick synopsis of where things stand…

Right now Gentoo is considerably behind upstream for MythTV. Gentoo’s latest stable is in the 0.22 branch, with 0.23 being in testing. Upstream considers 0.24.1 stable.

The good news is that upstream actually provides a Gentoo overlay which should make getting this into the tree relatively easy. The bad news is that MythTV and its plugins are heavily dependent on an eclass, and the upstream overlay eclass contains substantial changes (and is likely not backwards compatible with the ebuilds in the Gentoo tree).

Complicating things is the fact that the MythTV herd is pretty thin these days on Gentoo, with Cardoe being tied up with other things (as an aside – we all owe Cardoe thanks for sustaining things for this long). My own MythTV setup is also used by my family of four, which means that I don’t like to mess with it unless I have a solid weekend to deal with any issues that crop up, especially since my front-end runs minimyth which is itself problematic and needs to be kept in-sync since MythTV does not support cross-version client/server setups. A series of personal emergencies hasn’t really helped much either.

Still, our users do deserve better, and I’m eager to try out 0.24 myself. So, rather than slow things up by trying to consolidate the eclasses into something that is both forwards- and backwards-compatible I plan to just introduce a mythtv-2.eclass into the tree, and migrate over. Once the old builds are cleaned out the old eclass will no longer be used (removing it is a different matter for the longer-term).

Hopefully I’ll get a chance to upgrade to the version in upstream’s overlay soon, and once I’m reasonably confident that it is OK I’ll introduce it into the tree. It will likely be light on plugins initially unless I can find some willing testers – if you’re interested in helping out feel free to contact me offline or comment below.

So, sorry for the long wait. If you are in a hurry feel free to try out upstream’s overlay – unless it contains some major issue that is what Gentoo will end up with and it will be easy for you to switch over. Oh, and expect 0.24.1 to be the target for Gentoo – no sense starting out behind.

Filed under: gentoo

Kyle Winfree: Cucumber progress…

Tue, 14 Jun 2011 22:36:08 +0000

We have some cucumber flowers now, that’s a good sign.

Kyle Winfree: Hello World part two!

Thu, 09 Jun 2011 19:10:16 +0000

Woohoo. This is the second tutorial in learning to develop for Android, but running on a real device.

Kyle Winfree: Back to some silly techy fun

Thu, 09 Jun 2011 18:05:06 +0000

I have a project at school that involves using an Android based device (a tablet that runs a GNU-Linux based phone oriented operating system). For some reason, I thought setting up my development environment in Windows (should have gone with Mandriva) would be easiest. It took a few hours unfortunately, but it’s done! And wha-la, here is HelloAndroid as outlined at http://developer.android.com/resources/tutorials/hello-world.html.

HelloAndroid running in the Dalvik Virtual Machine

Kyle Winfree: The peppers got an upgrade

Mon, 06 Jun 2011 21:26:08 +0000

They were in a tiny pot, but V made sure they have room to grow. The additional beans are another gift from Carol. Thanks Carol!