Category Archives: General

Patent idea of the day…

This is probably a very obvious thought to those who wear glasses more frequently than I do…

Wouldn’t it be cool if you could get rotationally-polarised contact lenses? Then contact-lens wearers could just walk into 3D movies and not have to wear low-quality plastic glasses like the rest of us. It would probably be a much better experience.

I remember my mother telling me about visiting an African orphanage for young blind children, a long time ago. The children asked her to go into the dormitory and read them a bedtime story. When she got there, however, it was pitch black. The children didn’t need any lights to get ready for bed, but there was no way she could read them anything. So, instead, they pulled out their braille books and read her stories, a role-reversal which delighted everybody.

Well, maybe those of you who have had to put up with various eyesight-enhancement technologies and found them to be a nuisance in the past will soon have an advantage over those of us who can’t get retina-projected Google maps so easily…

Thanks to Richard Watts for prompting the idea…

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There should be a word for that…

Rose and I invented a new word this week. It’s a technical cycling term, so may not become widespread, but I think we may see rapid adoption of it in East Anglia and the Netherlands.

ishybutt (ˈɪʃibʌt) (also ishibutt)
noun the experience of sitting on a bicycle saddle, only to discover that it has been raining.

Hope you find it useful in daily conversation.

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LinkedIn foolishness

John's been writing about the somewhat bizarre practice of LinkedIn 'endorsements', where you can affirm that an acquaintance really has the skills they say they have.

Well, frankly, I wouldn't, in the first place, link to anyone I thought was likely to lie on their CV. I'm old-fashioned enough to remember the days when a LinkedIn connection was meant to imply some sort of endorsement in itself.

Interestingly, you can also endorse people's expertise in skills they never knew they had. I never listed any on my LinkedIn page until some kind friend said I was awfully good at 'Architecture', which I assume they meant in the sense of 'computer systems architecture', but, who knows, perhaps they had seen my old garden shed modifications? Hoping for some interesting job offers from that one.

It is, of course, a brilliant marketing trick on LinkedIn's part. In a world where page hit numbers are everything, it's hard to imagine a better email campaign to make users feel obliged to come back to your site over and over again.

When it all started, I added 'LinkedIn Endorsing' to my list of skills, and a couple of friends have kindly endorsed my abilities in that area. So maybe, by way of bringing a little festive cheer, I should be endorsing their LinkedIn-endorsing-endorsing?

 

Oh, and Happy Christmas, everybody!

 

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Feed on this…

For some years, I had a handy sign-up form on the right-hand side of Status-Q allowing you to receive new entries by email, thanks to the good folk at FeedMyInbox. Sadly, they’re going to be closing down at the end of the year. As an alternative, you can use IFTTT to create RSS-to-email recipes.

However, since the most-used RSS reader out there, by far, is Google Reader, and the various apps that can sync with it (my current iPad favourite being Reeder), I’ve replaced the FeedMyInbox link with an ‘Add to Google’ button, so it’s dead easy to include Status-Q in your Google feeds, should you so desire.

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Configuring GRUB to boot the right kernel after an upgrade

This is based on a very useful post by a chap named Arie. The credit for much of the following goes to him: I’m just reposting a summary to make it more widely discoverable.

If you upgrade your Linux installation, which on Ubuntu/Debian you might do with something like this:

sudo aptitude update
sudo aptitude safe-upgrade

then you may find that your kernel (linux-image package) and GRUB bootloader configuration have been updated. In particular, it may not now, by default, automatically select the right boot menu option when you next reboot… which you’re probably just about to do because you’ve just upgraded everything. This makes some sense because, if the upgrade failed for some reason, you may want to select a different option from the boot menu and go back to the previous kernel.

Well, it makes sense, unless, of course, you aren’t sitting in front of the machine with a screen and keyboard. If you’re upgrading a remote server, you may find that it doesn’t come back up after your reboot. In my case, the server was very remote, and I was lucky to have someone on site to press the right keys.

So, before you reboot after a new kernel installation, you may want to configure GRUB to try the new kernel automatically, and if it fails, go back to the old one.

GRUB is configured by the file /boot/grub/grub.cfg, but on a modern Ubuntu, rather than editing this big and complex file directly, you edit a few settings in /etc/default/grub, and then run update-grub to rebuild it out of lots of separate bits.

So, look at the variables in /etc/default/grub and make sure the following are set:

GRUB_DEFAULT=saved
GRUB_TIMEOUT=2
GRUB_CMDLINE_LINUX_DEFAULT=”panic=5″

This tells GRUB to use the last-saved selection, to boot it automatically after 2 seconds, and tells all kernels that they should reboot after 5 seconds if they die completely. Then you need to configure which kernel is initially the one that’s ‘saved’. Set it to be the one you know works. e.g.:

sudo grub-set-default "Ubuntu, with Linux 3.2.0-29-generic"

(You can look at the kernel you’re currently running with uname -a and find the label used to select it in /boot/grub/grub.cfg. Try grep menuentry /boot/grub/grub.cfg, for example.)

Then tell GRUB to try the new kernel on the next reboot, e.g.:

sudo grub-reboot ”Ubuntu, with Linux 3.2.0-32-new”

(This doesn’t actually do the reboot)

Then save all of these things using:

sudo update-grub

And try rebooting.

If it works OK and you come up in the new kernel, set that to be the saved default for the future:

sudo grub-set-default "Ubuntu, with Linux 3.2.0-32-new”

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DNG (Does Not Go)

I shoot almost all my photos in RAW format, which means that my important originals are in a variety of different formats: some Nikon, some Canon, some Panasonic. All of these are proprietary formats (though they’ve generally been reverse-engineered), and so not really ideal for long-term archiving.

It was for this reason that Adobe, some time ago, came up with the DNG — Digital Negative — format: an open standard intended for things like archiving. There are tools for converting most things into DNG, and the idea is that you’ll always be able to get your images out. Some cameras even save DNG as their native format. It’s a very good idea.

In theory.

The problem is that almost none of the tools I use support it. Adobe Lightroom does, of course, and makes it nice and easy to convert images automatically as you import them from your camera. But, once I have my image as a DNG, I find I can’t open it in Aperture, Preview, Acorn or even Photoshop CS3. I don’t get thumbnails in the Finder. I tried reverting to earlier, less efficient versions of the DNG format with fewer fancy options but it still didn’t help, unless you go back to really early variants, which can multiply the file size by three.

I could, of course, view my DNG files in Photoshop if I adopted the standard Adobe solution: pay hundreds of pounds to upgrade a product I paid hundreds of pounds for a little while ago. But I have the latest versions of other software products and none of them can open recent DNGs. Some of it may boil down to insufficient support in Apple’s underlying libraries. Whatever the reason, everything can open the closed, proprietary formats, whereas even Adobe’s DNG Converter can only convert to other forms of DNG. A few special tools like RPP can convert them to TIFFs, as long as you’re not using the latest DNG variants.

I’ve written about this before, but I repeat the experiment periodically to see if things have improved, because I really like the idea of storing things in an open raw format. But, sadly, at present, putting your files into DNG seems to imply locking yourself into expensive Adobe upgrades.

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Meet Tomahawk

It’s not often I’d voluntarily share an advertisement here… but this caught my eye despite my normal banner-ad blindness. I think it’s very nicely done – and hard to ignore!

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HBT

This morning, as I was getting ready for breakfast, I was contemplating what must, surely, be one of the finest phrases in the English language.

Not for its own intrinsic poetry, which I will grant you is minimal, nor indeed for the very pleasant experience it actually describes, but for all the additional images that it conjures up of comfort, safety, return from exciting adventures, and a sense that all is well with the world. Is there any other phrase that so encapsulates these ideals as the simple three words, hot buttered toast?

I think not.

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The grass is always greener

The tactics of queueing, beautifully illustrated in a simple animated GIF:

Seemed appropriate for Status-Q!

Many thanks to Martin Kleppmann for the link.

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Bayeswatch

OK — here's my deep thought for the day. Or it may not be deep, but I haven't finished my first coffee yet…

Is Hume's Maxim simply a restatement of Bayesian Inference?

I'm sure this is not a new idea, but I hadn't made the connection before. Hume's Maxim, which I've always liked, basically states that:

no testimony is sufficient to establish the existence of a miracle, unless it is more likely that the miracle occurred than that the testimony was false.

(I paraphrase slightly. More info here.)

Bayes' Rule is a little more complex, so hang while I just make some more coffee… Ok. Brace yourself. This won't hurt much.

It's the following equation:

where P ( X | Y ) means 'the probability of X given Y'. It’s often written using H and E for hypothesis and evidence.

It says that you can calculate the probability of a hypothesis (say, that a miracle occurred) given some piece of evidence (Mrs Jones reports having seen it).

The probability will depend on three things in the right-hand side of the equation:

  • P(H) – The probability of the miracle itself independent of any reports. (e.g. did the laws of physics change on this particular day for Mrs Jones?)
  • P(E) – The probability that the evidence would present itself independent of anything actually occurring. The combination of possibilities that Mrs Jones was either mistaken, deceived, deluded, fibbing or had some other motivation — possibly a perfectly good one — for coming up with such a report in any case.
  • P(E|H) – The likelihood that Mrs Jones would have reported a miracle, given that it actually occurred. Well, we’re not interested in miracles that happen quietly in the middle of a wood somewhere. We’re talking here about miracles for which there is testimony, so this term is probably 1 or close to it* and so can be removed from the equation in this case. David Hume didn’t include it. It’s worth noting, though, that if people are often abducted by aliens and neglect to mention it, you need to take that into account when they do.

If the likelihood of the laws of physics changing are greater than that Mrs Jones’s report is mistaken – i.e. that P ( H ) is greater than P ( E ) – then the probability that the miracle occurred, given her testimony, is greater than one – i.e. her testimony has established the veracity of the miracle.

So the statements are saying very similar things. Interestingly, they date from about the same period, too – late 18th century – and show an unusual overlap of two magesteria – philosphy and mathematics.

For such a simple equation, Bayes' Rule is incredibly powerful, though its revelations can sometimes be hard to grasp intuitively. You benefit from it every day, though, because it turns out to be phenomenally good, for example, at working out the likelihood that a given piece of email is spam. And a deep understanding of it, combined with a good marketing team, was the foundation of Autonomy, the Cambridge company sold to Hewlett-Packard last year for $10bn.

Sadly, it isn't used often enough for assessing the reliability of conspiracy theories and Daily Mail articles, perhaps because it doesn't tend to stick in one's mind.

So for normal, day-to-day understanding of the world around you, I recommend David Hume's version.

* Update: The probability that I will get statistics correct without help is about the same as the probability that Status-Q’s author is more intelligent than its readers. Thomas points out, quite rightly, that a probability can’t be greater than 1 – something that had been bothering me a bit too! P(E|H) is always less than P(E), so all this is really saying is that the likelihood of a miracle having occurred given Mrs Jones’s report is a bit less than the likelihood of a miracle having occurred. I may be pushing a few things too far: not least my understanding of stats. Hume is talking about the relative values of P(x), not the relationship between them. Can we draw anything more from this? A topic for discussion…!

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Radio Days

Tonight I gave a talk about the Raspberry Pi to the Cambridge and District Amateur Radio Club. I pointed out that I didn't really belong in the group, unless you stretch the word 'Amateur' almost to breaking point, for I know almost nothing about radio.

But I understand the appeal. I made little crystal sets as a child and discovered that the aluminium double-glazing frame in my bedroom was an astonishingly good aerial, provided you wanted to listen to BBC Radio 2. Any other station was likely to be disappointing, but this it received so well that I could almost just connect high-impedance headphones to the frame without any other components. I read, with great jealousy, American novels where the kids had adventures involving walkie-talkies. Many years later, the opening up of CB radio and other bands here in the UK made such things a possibility, but for me, radio was something you received, not transmitted.

On a couple of occasions, visiting a friend or distant family member, I was taken out to a 'shack' in the back garden and allowed to watch and even participate in the strange ritual of starting up shelves of valve–powered equipment, which existed to connect a little speaker and microphone, via an enormous roof-mounted antenna, to people in far-flung parts of the country or even, if atmospheric conditions were right, of the globe.

What I realise now, of course, is what these guys were doing. These were the ones who weren't the passive consumers of radio technology like the rest of us. They had gone to the trouble to amass the equipment and expertise to be allowed to transmit as well as receive. And what were they doing with it?

Late at night, decades before Mr Zuckerberg was even born, they were disappearing into their strange dens to engage in global social networking.

 

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Listening for the word

Since I turned on my Mac’s firewall a few months ago, I get occasional messages which cause me to wonder:

Now, I can understand why Word might want to make outgoing connections, to check for version updates, to print, etc. Anyone know why it would want to be listening on my network? It works just fine if you say no, but I am curious…

The other revealing thing, for me, was that I only saw this message today, which means I haven’t used Microsoft Word for more than four months. This time, as is usually the case, I only need to run it when I’m sent something by a lawyer.

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